Improving README.

NSUserDefaults does not support KVO officially.

LICENSE

@@ -0,0 +1,22 @@
+Copyright (c) 2012-2013, Vadim Shpakovski
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

MASShortcut+Monitoring.h

@@ -0,0 +1,8 @@
+#import "MASShortcut.h"
+
+@interface MASShortcut (Monitoring)
+
++ (id)addGlobalHotkeyMonitorWithShortcut:(MASShortcut *)shortcut handler:(void (^)())handler;
++ (void)removeGlobalHotkeyMonitor:(id)monitor;
+
+@end

MASShortcut+Monitoring.m

@@ -0,0 +1,165 @@
+#import "MASShortcut+Monitoring.h"
+
+NSMutableDictionary *MASRegisteredHotKeys();
+BOOL InstallCommonEventHandler();
+BOOL InstallHotkeyWithShortcut(MASShortcut *shortcut, UInt32 *outCarbonHotKeyID, EventHotKeyRef *outCarbonHotKey);
+void UninstallEventHandler();
+
+#pragma mark -
+
+@interface MASShortcutHotKey : NSObject
+
+@property (nonatomic, readonly) MASShortcut *shortcut;
+@property (nonatomic, readonly, copy) void (^handler)();
+@property (nonatomic, readonly) EventHotKeyRef carbonHotKey;
+@property (nonatomic, readonly) UInt32 carbonHotKeyID;
+
+- (id)initWithShortcut:(MASShortcut *)shortcut handler:(void (^)())handler;
+
+@end
+
+#pragma mark -
+
+@implementation MASShortcut (Monitoring)
+
++ (id)addGlobalHotkeyMonitorWithShortcut:(MASShortcut *)shortcut handler:(void (^)())handler
+{
+    NSString *monitor = [NSString stringWithFormat:@"%@", shortcut.description];
+    if ([MASRegisteredHotKeys() objectForKey:monitor]) return nil;
+
+    MASShortcutHotKey *hotKey = [[MASShortcutHotKey alloc] initWithShortcut:shortcut handler:handler];
+    if (hotKey == nil) return nil;
+
+    [MASRegisteredHotKeys() setObject:hotKey forKey:monitor];
+    return monitor;
+}
+
++ (void)removeGlobalHotkeyMonitor:(id)monitor
+{
+    if (monitor == nil) return;
+    NSMutableDictionary *registeredHotKeys = MASRegisteredHotKeys();
+    [registeredHotKeys removeObjectForKey:monitor];
+    if (registeredHotKeys.count == 0) {
+        UninstallEventHandler();
+    }
+}
+
+@end
+
+#pragma mark -
+
+@implementation MASShortcutHotKey
+
+@synthesize carbonHotKeyID = _carbonHotKeyID;
+@synthesize handler = _handler;
+@synthesize shortcut = _shortcut;
+@synthesize carbonHotKey = _carbonHotKey;
+
+#pragma mark -
+
+- (id)initWithShortcut:(MASShortcut *)shortcut handler:(void (^)())handler
+{
+    self = [super init];
+    if (self) {
+        _shortcut = shortcut;
+        _handler = [handler copy];
+
+        if (!InstallHotkeyWithShortcut(shortcut, &_carbonHotKeyID, &_carbonHotKey))
+            self = nil;
+    }
+    return self;
+}
+
+- (void)dealloc
+{
+    [self uninstallExisitingHotKey];
+}
+
+- (void)uninstallExisitingHotKey
+{
+    if (_carbonHotKey) {
+        UnregisterEventHotKey(_carbonHotKey);
+        _carbonHotKey = NULL;
+    }
+}
+
+@end
+
+#pragma mark - Carbon magic
+
+NSMutableDictionary *MASRegisteredHotKeys()
+{
+    static NSMutableDictionary *shared = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        shared = [NSMutableDictionary dictionary];
+    });
+    return shared;
+}
+
+#pragma mark -
+
+FourCharCode const kMASShortcutSignature = 'MASS';
+
+BOOL InstallHotkeyWithShortcut(MASShortcut *shortcut, UInt32 *outCarbonHotKeyID, EventHotKeyRef *outCarbonHotKey)
+{
+    if ((shortcut == nil) || !InstallCommonEventHandler()) return NO;
+
+    static UInt32 sCarbonHotKeyID = 0;
+	EventHotKeyID hotKeyID = { .signature = kMASShortcutSignature, .id = ++ sCarbonHotKeyID };
+    EventHotKeyRef carbonHotKey = NULL;
+    if (RegisterEventHotKey(shortcut.carbonKeyCode, shortcut.carbonFlags, hotKeyID, GetEventDispatcherTarget(), kEventHotKeyExclusive, &carbonHotKey) != noErr) {
+        return NO;
+    }
+
+    if (outCarbonHotKeyID) *outCarbonHotKeyID = hotKeyID.id;
+    if (outCarbonHotKey) *outCarbonHotKey = carbonHotKey;
+    return YES;
+}
+
+static OSStatus CarbonCallback(EventHandlerCallRef inHandlerCallRef, EventRef inEvent, void *inUserData)
+{
+	if (GetEventClass(inEvent) != kEventClassKeyboard) return noErr;
+
+	EventHotKeyID hotKeyID;
+	OSStatus status = GetEventParameter(inEvent, kEventParamDirectObject, typeEventHotKeyID, NULL, sizeof(hotKeyID), NULL, &hotKeyID);
+	if (status != noErr) return status;
+
+	if (hotKeyID.signature != kMASShortcutSignature) return noErr;
+
+    [MASRegisteredHotKeys() enumerateKeysAndObjectsUsingBlock:^(id key, MASShortcutHotKey *hotKey, BOOL *stop) {
+        if (hotKeyID.id == hotKey.carbonHotKeyID) {
+            if (hotKey.handler) {
+                hotKey.handler();
+            }
+            *stop = YES;
+        }
+    }];
+
+	return noErr;
+}
+
+#pragma mark -
+
+static EventHandlerRef sEventHandler = NULL;
+
+BOOL InstallCommonEventHandler()
+{
+    if (sEventHandler == NULL) {
+        EventTypeSpec hotKeyPressedSpec = { .eventClass = kEventClassKeyboard, .eventKind = kEventHotKeyPressed };
+        OSStatus status = InstallEventHandler(GetEventDispatcherTarget(), CarbonCallback, 1, &hotKeyPressedSpec, NULL, &sEventHandler);
+        if (status != noErr) {
+            sEventHandler = NULL;
+            return NO;
+        }
+    }
+    return YES;
+}
+
+void UninstallEventHandler()
+{
+    if (sEventHandler) {
+        RemoveEventHandler(sEventHandler);
+        sEventHandler = NULL;
+    }
+}

MASShortcut+UserDefaults.h

@@ -4,6 +4,6 @@
 
 + (void)registerGlobalShortcutWithUserDefaultsKey:(NSString *)userDefaultsKey handler:(void (^)())handler;
 + (void)unregisterGlobalShortcutWithUserDefaultsKey:(NSString *)userDefaultsKey;
-
++ (void)setGlobalShortcut:(MASShortcut *)shortcut forUserDefaultsKey:(NSString *)userDefaultsKey;
 
 @end

MASShortcut+UserDefaults.m

@@ -1,23 +1,21 @@
 #import "MASShortcut+UserDefaults.h"
+#import "MASShortcut+Monitoring.h"
 
-@interface MASShortcutHotKey : NSObject
+@interface MASShortcutUserDefaultsHotKey : NSObject
 
 @property (nonatomic, readonly) NSString *userDefaultsKey;
-@property (nonatomic, readonly, copy) void (^handler)();
-@property (nonatomic, readonly) EventHotKeyRef carbonHotKey;
-@property (nonatomic, readonly) UInt32 carbonHotKeyID;
+@property (nonatomic, copy) void (^handler)();
+@property (nonatomic, weak) id monitor;
 
 - (id)initWithUserDefaultsKey:(NSString *)userDefaultsKey handler:(void (^)())handler;
 
-+ (void)uninstallEventHandler;
-
 @end
 
 #pragma mark -
 
 @implementation MASShortcut (UserDefaults)
 
-+ (NSMutableDictionary *)registeredHotKeys
++ (NSMutableDictionary *)registeredUserDefaultsHotKeys
 {
     static NSMutableDictionary *shared = nil;
     static dispatch_once_t onceToken;
@@ -29,130 +27,78 @@
 
 + (void)registerGlobalShortcutWithUserDefaultsKey:(NSString *)userDefaultsKey handler:(void (^)())handler;
 {
-    MASShortcutHotKey *hotKey = [[MASShortcutHotKey alloc] initWithUserDefaultsKey:userDefaultsKey handler:handler];
-    [[self registeredHotKeys] setObject:hotKey forKey:userDefaultsKey];
+    MASShortcutUserDefaultsHotKey *hotKey = [[MASShortcutUserDefaultsHotKey alloc] initWithUserDefaultsKey:userDefaultsKey handler:handler];
+    [[self registeredUserDefaultsHotKeys] setObject:hotKey forKey:userDefaultsKey];
 }
 
 + (void)unregisterGlobalShortcutWithUserDefaultsKey:(NSString *)userDefaultsKey
 {
-    NSMutableDictionary *registeredHotKeys = [self registeredHotKeys];
+    NSMutableDictionary *registeredHotKeys = [self registeredUserDefaultsHotKeys];
     [registeredHotKeys removeObjectForKey:userDefaultsKey];
-    if (registeredHotKeys.count == 0) {
-        [MASShortcutHotKey uninstallEventHandler];
-    }
+}
+
++ (void)setGlobalShortcut:(MASShortcut *)shortcut forUserDefaultsKey:(NSString *)userDefaultsKey
+{
+    NSData *shortcutData = shortcut.data;
+    if (shortcutData)
+        [[NSUserDefaults standardUserDefaults] setObject:shortcutData forKey:userDefaultsKey];
+    else
+        [[NSUserDefaults standardUserDefaults] removeObjectForKey:userDefaultsKey];
 }
 
 @end
 
 #pragma mark -
 
-@implementation MASShortcutHotKey
+@implementation MASShortcutUserDefaultsHotKey {
+    NSString *_observableKeyPath;
+}
 
-@synthesize carbonHotKeyID = _carbonHotKeyID;
+@synthesize monitor = _monitor;
 @synthesize handler = _handler;
 @synthesize userDefaultsKey = _userDefaultsKey;
-@synthesize carbonHotKey = _carbonHotKey;
 
 #pragma mark -
 
+void *MASShortcutUserDefaultsContext = &MASShortcutUserDefaultsContext;
+
 - (id)initWithUserDefaultsKey:(NSString *)userDefaultsKey handler:(void (^)())handler
 {
     self = [super init];
     if (self) {
         _userDefaultsKey = userDefaultsKey.copy;
         _handler = [handler copy];
-        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(userDefaultsDidChange:)
-                                                     name:NSUserDefaultsDidChangeNotification object:[NSUserDefaults standardUserDefaults]];
-        [self installHotKeyFromUserDefaults];
+        _observableKeyPath = [@"values." stringByAppendingString:_userDefaultsKey];
+        [[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:_observableKeyPath options:NSKeyValueObservingOptionInitial context:MASShortcutUserDefaultsContext];
     }
     return self;
 }
 
 - (void)dealloc
 {
-    [[NSNotificationCenter defaultCenter] removeObserver:self name:NSUserDefaultsDidChangeNotification object:[NSUserDefaults standardUserDefaults]];
-    [self uninstallExisitingHotKey];
+    [[NSUserDefaultsController sharedUserDefaultsController] removeObserver:self forKeyPath:_observableKeyPath context:MASShortcutUserDefaultsContext];
+    [MASShortcut removeGlobalHotkeyMonitor:self.monitor];
 }
 
 #pragma mark -
 
-- (void)userDefaultsDidChange:(NSNotification *)note
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
 {
-    [self uninstallExisitingHotKey];
-    [self installHotKeyFromUserDefaults];
-}
-
-#pragma mark - Carbon events
-
-static EventHandlerRef sEventHandler = NULL;
-
-+ (BOOL)installCommonEventHandler
-{
-    if (sEventHandler == NULL) {
-        EventTypeSpec hotKeyPressedSpec = { .eventClass = kEventClassKeyboard, .eventKind = kEventHotKeyPressed };
-        OSStatus status = InstallEventHandler(GetEventDispatcherTarget(), CarbonCallback, 1, &hotKeyPressedSpec, NULL, &sEventHandler);
-        if (status != noErr) {
-            sEventHandler = NULL;
-            return NO;
-        }
+    if (context == MASShortcutUserDefaultsContext) {
+        [MASShortcut removeGlobalHotkeyMonitor:self.monitor];
+        [self installHotKeyFromUserDefaults];
     }
-    return YES;
-}
-
-+ (void)uninstallEventHandler
-{
-    if (sEventHandler) {
-        RemoveEventHandler(sEventHandler);
-        sEventHandler = NULL;
+    else {
+        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
     }
 }
 
-#pragma mark -
-
-- (void)uninstallExisitingHotKey
-{
-    if (_carbonHotKey) {
-        UnregisterEventHotKey(_carbonHotKey);
-        _carbonHotKey = NULL;
-    }
-}
-
-FourCharCode const kMASShortcutSignature = 'MASS';
-
 - (void)installHotKeyFromUserDefaults
 {
     NSData *data = [[NSUserDefaults standardUserDefaults] dataForKey:_userDefaultsKey];
     MASShortcut *shortcut = [MASShortcut shortcutWithData:data];
-    if ((shortcut == nil) || ![[self class] installCommonEventHandler]) return;
-
-    static UInt32 sCarbonHotKeyID = 0;
-    _carbonHotKeyID = ++ sCarbonHotKeyID;
-	EventHotKeyID hotKeyID = { .signature = kMASShortcutSignature, .id = _carbonHotKeyID };
-    if (RegisterEventHotKey(shortcut.carbonKeyCode, shortcut.carbonFlags, hotKeyID, GetEventDispatcherTarget(), kEventHotKeyExclusive, &_carbonHotKey) != noErr) {
-        _carbonHotKey = NULL;
-    }
+    if (shortcut == nil) return;
+    self.monitor = [MASShortcut addGlobalHotkeyMonitorWithShortcut:shortcut handler:self.handler];
 }
 
-static OSStatus CarbonCallback(EventHandlerCallRef inHandlerCallRef, EventRef inEvent, void *inUserData)
-{
-	if (GetEventClass(inEvent) != kEventClassKeyboard) return noErr;
-
-	EventHotKeyID hotKeyID;
-	OSStatus status = GetEventParameter(inEvent, kEventParamDirectObject, typeEventHotKeyID, NULL, sizeof(hotKeyID), NULL, &hotKeyID);
-	if (status != noErr) return status;
-
-	if (hotKeyID.signature != kMASShortcutSignature) return noErr;
-
-    [[MASShortcut registeredHotKeys] enumerateKeysAndObjectsUsingBlock:^(id key, MASShortcutHotKey *hotKey, BOOL *stop) {
-        if (hotKeyID.id == hotKey.carbonHotKeyID) {
-            if (hotKey.handler) {
-                hotKey.handler();
-            }
-            *stop = YES;
-        }
-    }];
-
-	return noErr;
-}
-
-@end
+@end

MASShortcut.h

@@ -37,6 +37,7 @@ enum {
 @property (nonatomic, readonly) UInt32 carbonKeyCode;
 @property (nonatomic, readonly) UInt32 carbonFlags;
 @property (nonatomic, readonly) NSString *keyCodeString;
+@property (nonatomic, readonly) NSString *keyCodeStringForKeyEquivalent;
 @property (nonatomic, readonly) NSString *modifierFlagsString;
 @property (nonatomic, readonly) NSData *data;
 @property (nonatomic, readonly) BOOL shouldBypass;
@@ -50,4 +51,9 @@ enum {
 
 - (BOOL)isTakenError:(NSError **)error;
 
+// The following API enable hotkeys with the Option key as the only modifier
+// For example, Option-G will not generate © and Option-R will not paste ®
++ (void)setAllowsAnyHotkeyWithOptionModifier:(BOOL)allow;
++ (BOOL)allowsAnyHotkeyWithOptionModifier;
+
 @end

MASShortcut.m

@@ -1,7 +1,7 @@
 #import "MASShortcut.h"
 
-NSString *const kMASShortcutKeyCode = @"KeyCode";
-NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
+NSString *const MASShortcutKeyCode = @"KeyCode";
+NSString *const MASShortcutModifierFlags = @"ModifierFlags";
 
 @implementation MASShortcut {
     NSUInteger _keyCode; // NSNotFound if empty
@@ -15,17 +15,17 @@ NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
 
 - (void)encodeWithCoder:(NSCoder *)coder
 {
-    [coder encodeInteger:(self.keyCode != NSNotFound ? (NSInteger)self.keyCode : - 1) forKey:kMASShortcutKeyCode];
-    [coder encodeInteger:(NSInteger)self.modifierFlags forKey:kMASShortcutModifierFlags];
+    [coder encodeInteger:(self.keyCode != NSNotFound ? (NSInteger)self.keyCode : - 1) forKey:MASShortcutKeyCode];
+    [coder encodeInteger:(NSInteger)self.modifierFlags forKey:MASShortcutModifierFlags];
 }
 
 - (id)initWithCoder:(NSCoder *)decoder
 {
     self = [super init];
     if (self) {
-        NSInteger code = [decoder decodeIntegerForKey:kMASShortcutKeyCode];
+        NSInteger code = [decoder decodeIntegerForKey:MASShortcutKeyCode];
         self.keyCode = (code < 0 ? NSNotFound : (NSUInteger)code);
-        self.modifierFlags = [decoder decodeIntegerForKey:kMASShortcutModifierFlags];
+        self.modifierFlags = [decoder decodeIntegerForKey:MASShortcutModifierFlags];
     }
     return self;
 }
@@ -52,7 +52,8 @@ NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
 
 + (MASShortcut *)shortcutWithData:(NSData *)data
 {
-    return (data ? (MASShortcut *)[NSKeyedUnarchiver unarchiveObjectWithData:data] : nil);
+    id shortcut = (data ? [NSKeyedUnarchiver unarchiveObjectWithData:data] : nil);
+    return shortcut;
 }
 
 #pragma mark - Shortcut accessors
@@ -82,6 +83,38 @@ NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
     return [NSString stringWithFormat:@"%@%@", self.modifierFlagsString, self.keyCodeString];
 }
 
+- (NSString *)keyCodeStringForKeyEquivalent
+{
+    NSString *keyCodeString = self.keyCodeString;
+    if (keyCodeString.length > 1) {
+        switch (self.keyCode) {
+            case kVK_F1: return MASShortcutChar(0xF704);
+            case kVK_F2: return MASShortcutChar(0xF705);
+            case kVK_F3: return MASShortcutChar(0xF706);
+            case kVK_F4: return MASShortcutChar(0xF707);
+            case kVK_F5: return MASShortcutChar(0xF708);
+            case kVK_F6: return MASShortcutChar(0xF709);
+            case kVK_F7: return MASShortcutChar(0xF70a);
+            case kVK_F8: return MASShortcutChar(0xF70b);
+            case kVK_F9: return MASShortcutChar(0xF70c);
+            case kVK_F10: return MASShortcutChar(0xF70d);
+            case kVK_F11: return MASShortcutChar(0xF70e);
+            case kVK_F12: return MASShortcutChar(0xF70f);
+            // From this point down I am guessing F13 etc come sequentially, I don't have a keyboard to test.
+            case kVK_F13: return MASShortcutChar(0xF710);
+            case kVK_F14: return MASShortcutChar(0xF711);
+            case kVK_F15: return MASShortcutChar(0xF712);
+            case kVK_F16: return MASShortcutChar(0xF713);
+            case kVK_F17: return MASShortcutChar(0xF714);
+            case kVK_F18: return MASShortcutChar(0xF715);
+            case kVK_F19: return MASShortcutChar(0xF716);
+            case kVK_Space: return MASShortcutChar(0x20);
+            default: return @"";
+        }
+    }
+    return keyCodeString.lowercaseString;
+}
+
 - (NSString *)keyCodeString
 {
     // Some key codes don't have an equivalent
@@ -103,6 +136,9 @@ NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
         case kVK_F14: return @"F14";
         case kVK_F15: return @"F15";
         case kVK_F16: return @"F16";
+        case kVK_F17: return @"F17";
+        case kVK_F18: return @"F18";
+        case kVK_F19: return @"F19";
         case kVK_Space: return NSLocalizedString(@"Space", @"Shortcut glyph name for SPACE key");
         case kVK_Escape: return MASShortcutChar(kMASShortcutGlyphEscape);
         case kVK_Delete: return MASShortcutChar(kMASShortcutGlyphDeleteLeft);
@@ -202,19 +238,50 @@ NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
     return (self.modifierFlags == NSCommandKeyMask) && ([codeString isEqualToString:@"W"] || [codeString isEqualToString:@"Q"]);
 }
 
+BOOL MASShortcutAllowsAnyHotkeyWithOptionModifier = NO;
+
++ (void)setAllowsAnyHotkeyWithOptionModifier:(BOOL)allow
+{
+    MASShortcutAllowsAnyHotkeyWithOptionModifier = allow;
+}
+
++ (BOOL)allowsAnyHotkeyWithOptionModifier
+{
+    return MASShortcutAllowsAnyHotkeyWithOptionModifier;
+}
+
 - (BOOL)isValid
 {
-    BOOL hasFlags = (_modifierFlags > 0);
-    BOOL hasCommand = ((_modifierFlags & NSCommandKeyMask) > 0);
-    BOOL hasControl = ((_modifierFlags & NSControlKeyMask) > 0);
-    BOOL hasOption = ((_modifierFlags & NSAlternateKeyMask) > 0);
-    BOOL isFunction = ((_keyCode == kVK_F1) || (_keyCode == kVK_F2) || (_keyCode == kVK_F3) || (_keyCode == kVK_F4) ||
-                       (_keyCode == kVK_F5) || (_keyCode == kVK_F6) || (_keyCode == kVK_F7) || (_keyCode == kVK_F8) ||
-                       (_keyCode == kVK_F9) || (_keyCode == kVK_F10) || (_keyCode == kVK_F11) || (_keyCode == kVK_F12) ||
-                       (_keyCode == kVK_F13) || (_keyCode == kVK_F14) || (_keyCode == kVK_F15) || (_keyCode == kVK_F16) ||
-                       (_keyCode == kVK_F17) || (_keyCode == kVK_F18) || (_keyCode == kVK_F19) || (_keyCode == kVK_F20));
-    BOOL isSpecial = ((_keyCode == kVK_Space) || (_keyCode == kVK_Escape) || (_keyCode == kVK_Return));
-    return ((hasFlags && (hasCommand || hasControl || (hasOption && isSpecial))) || isFunction);
+    // Allow any function key with any combination of modifiers
+    BOOL includesFunctionKey = ((_keyCode == kVK_F1) || (_keyCode == kVK_F2) || (_keyCode == kVK_F3) || (_keyCode == kVK_F4) ||
+                                (_keyCode == kVK_F5) || (_keyCode == kVK_F6) || (_keyCode == kVK_F7) || (_keyCode == kVK_F8) ||
+                                (_keyCode == kVK_F9) || (_keyCode == kVK_F10) || (_keyCode == kVK_F11) || (_keyCode == kVK_F12) ||
+                                (_keyCode == kVK_F13) || (_keyCode == kVK_F14) || (_keyCode == kVK_F15) || (_keyCode == kVK_F16) ||
+                                (_keyCode == kVK_F17) || (_keyCode == kVK_F18) || (_keyCode == kVK_F19) || (_keyCode == kVK_F20));
+    if (includesFunctionKey) return YES;
+
+    // Do not allow any other key without modifiers
+    BOOL hasModifierFlags = (_modifierFlags > 0);
+    if (!hasModifierFlags) return NO;
+
+    // Allow any hotkey containing Control or Command modifier
+    BOOL includesCommand = ((_modifierFlags & NSCommandKeyMask) > 0);
+    BOOL includesControl = ((_modifierFlags & NSControlKeyMask) > 0);
+    if (includesCommand || includesControl) return YES;
+
+    // Allow Option key only in selected cases
+    BOOL includesOption = ((_modifierFlags & NSAlternateKeyMask) > 0);
+    if (includesOption) {
+
+        // Always allow Option-Space and Option-Escape because they do not have any bind system commands
+        if ((_keyCode == kVK_Space) || (_keyCode == kVK_Escape)) return YES;
+
+        // Allow Option modifier with any key even if it will break the system binding
+        if ([[self class] allowsAnyHotkeyWithOptionModifier]) return YES;
+    }
+
+    // The hotkey does not have any modifiers or violates system bindings
+    return NO;
 }
 
 - (BOOL)isKeyEquivalent:(NSString *)keyEquivalent flags:(NSUInteger)flags takenInMenu:(NSMenu *)menu error:(NSError **)outError
@@ -223,10 +290,17 @@ NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
         if (menuItem.hasSubmenu && [self isKeyEquivalent:keyEquivalent flags:flags takenInMenu:menuItem.submenu error:outError]) return YES;
         
         BOOL equalFlags = (MASShortcutClear(menuItem.keyEquivalentModifierMask) == flags);
-        BOOL equalHotkey = [menuItem.keyEquivalent.uppercaseString isEqualToString:keyEquivalent];
-        if (equalFlags && equalHotkey) {
+        BOOL equalHotkeyLowercase = [menuItem.keyEquivalent.lowercaseString isEqualToString:keyEquivalent];
+        
+        // Check if the cases are different, we know ours is lower and that shift is included in our modifiers
+        // If theirs is capitol, we need to add shift to their modifiers
+        if (equalHotkeyLowercase && ![menuItem.keyEquivalent isEqualToString:keyEquivalent]) {
+            equalFlags = (MASShortcutClear(menuItem.keyEquivalentModifierMask | NSShiftKeyMask) == flags);
+        }
+        
+        if (equalFlags && equalHotkeyLowercase) {
             if (outError) {
-                NSString *format = NSLocalizedString(@"This shortcut cannot be used used because it is already used by the menu item ‘%@’.",
+                NSString *format = NSLocalizedString(@"This shortcut cannot be used because it is already used by the menu item ‘%@’.",
                                                      @"Message for alert when shortcut is already used");
                 NSDictionary *info = [NSDictionary dictionaryWithObject:[NSString stringWithFormat:format, menuItem.title]
                                                                  forKey:NSLocalizedDescriptionKey];
@@ -253,7 +327,7 @@ NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
                 ([(__bridge NSNumber *)flags unsignedIntegerValue] == self.carbonFlags)) {
 
                 if (outError) {
-                    NSString *description = NSLocalizedString(@"This combination cannot be used used because it is already used by a system-wide "
+                    NSString *description = NSLocalizedString(@"This combination cannot be used because it is already used by a system-wide "
                                                               @"keyboard shortcut.\nIf you really want to use this key combination, most shortcuts "
                                                               @"can be changed in the Keyboard & Mouse panel in System Preferences.",
                                                               @"Message for alert when shortcut is already used by the system");
@@ -265,7 +339,7 @@ NSString *const kMASShortcutModifierFlags = @"ModifierFlags";
         }
         CFRelease(globalHotKeys);
     }
-    return [self isKeyEquivalent:self.keyCodeString flags:self.modifierFlags takenInMenu:[NSApp mainMenu] error:outError];
+    return [self isKeyEquivalent:self.keyCodeStringForKeyEquivalent flags:self.modifierFlags takenInMenu:[NSApp mainMenu] error:outError];
 }
 
 @end

MASShortcutView+UserDefaults.m

@@ -15,18 +15,24 @@
 
 @implementation MASShortcutView (UserDefaults)
 
-void *kDefaultsObserver = &kDefaultsObserver;
+void *MASAssociatedDefaultsObserver = &MASAssociatedDefaultsObserver;
 
 - (NSString *)associatedUserDefaultsKey
 {
-    MASShortcutDefaultsObserver *defaultsObserver = objc_getAssociatedObject(self, kDefaultsObserver);
+    MASShortcutDefaultsObserver *defaultsObserver = objc_getAssociatedObject(self, MASAssociatedDefaultsObserver);
     return defaultsObserver.userDefaultsKey;
 }
 
 - (void)setAssociatedUserDefaultsKey:(NSString *)associatedUserDefaultsKey
 {
+    // First, stop observing previous shortcut view
+    objc_setAssociatedObject(self, MASAssociatedDefaultsObserver, nil, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+
+    if (associatedUserDefaultsKey.length == 0) return;
+
+    // Next, start observing current shortcut view
     MASShortcutDefaultsObserver *defaultsObserver = [[MASShortcutDefaultsObserver alloc] initWithShortcutView:self userDefaultsKey:associatedUserDefaultsKey];
-    objc_setAssociatedObject(self, kDefaultsObserver, defaultsObserver, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+    objc_setAssociatedObject(self, MASAssociatedDefaultsObserver, defaultsObserver, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
 }
 
 @end
@@ -109,7 +115,11 @@ void *kShortcutValueObserver = &kShortcutValueObserver;
         if (_internalShortcutChange) return;
         MASShortcut *shortcut = [object valueForKey:keyPath];
         _internalPreferenceChange = YES;
-        [[NSUserDefaults standardUserDefaults] setObject:shortcut.data forKey:_userDefaultsKey];
+
+        NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
+        [defaults setObject:(shortcut.data ?: [NSKeyedArchiver archivedDataWithRootObject:nil]) forKey:_userDefaultsKey];
+        [defaults synchronize];
+
         _internalPreferenceChange = NO;
     }
     else {

MASShortcutView.h

@@ -1,8 +1,9 @@
 @class MASShortcut;
 
 typedef enum {
-    MASShortcutViewAppearanceDefault = 0,
-    MASShortcutViewAppearanceTexturedRect
+    MASShortcutViewAppearanceDefault = 0,  // Height = 19 px
+    MASShortcutViewAppearanceTexturedRect, // Height = 25 px
+    MASShortcutViewAppearanceRounded       // Height = 43 px
 } MASShortcutViewAppearance;
 
 @interface MASShortcutView : NSView

MASShortcutView.m

@@ -83,6 +83,10 @@
             _shortcutCell.bezelStyle = NSTexturedRoundedBezelStyle;
             break;
         }
+        case MASShortcutViewAppearanceRounded: {
+            _shortcutCell.bezelStyle = NSRoundedBezelStyle;
+            break;
+        }
     }
 }
 
@@ -148,6 +152,10 @@
             [_shortcutCell drawWithFrame:CGRectOffset(frame, 0.0, 1.0) inView:self];
             break;
         }
+        case MASShortcutViewAppearanceRounded: {
+            [_shortcutCell drawWithFrame:CGRectOffset(frame, 0.0, 1.0) inView:self];
+            break;
+        }
     }
 }
 
@@ -161,7 +169,7 @@
         [self getShortcutRect:&shortcutRect hintRect:NULL];
         NSString *title = (self.recording
                            ? (_hinting
-                              ? NSLocalizedString(@"Use Old Shortuct", @"Cancel action button for non-empty shortcut in recording state")
+                              ? NSLocalizedString(@"Use Old Shortcut", @"Cancel action button for non-empty shortcut in recording state")
                               : (self.shortcutPlaceholder.length > 0
                                  ? self.shortcutPlaceholder
                                  : NSLocalizedString(@"Type New Shortcut", @"Non-empty shortcut button in recording state")))
@@ -195,7 +203,13 @@
 - (void)getShortcutRect:(CGRect *)shortcutRectRef hintRect:(CGRect *)hintRectRef
 {
     CGRect shortcutRect, hintRect;
-    CGRectDivide(self.bounds, &hintRect, &shortcutRect, HINT_BUTTON_WIDTH, CGRectMaxXEdge);
+    CGFloat hintButtonWidth = HINT_BUTTON_WIDTH;
+    switch (self.appearance) {
+        case MASShortcutViewAppearanceTexturedRect: hintButtonWidth += 2.0; break;
+        case MASShortcutViewAppearanceRounded: hintButtonWidth += 3.0; break;
+        default: break;
+    }
+    CGRectDivide(self.bounds, &hintRect, &shortcutRect, hintButtonWidth, CGRectMaxXEdge);
     if (shortcutRectRef)  *shortcutRectRef = shortcutRect;
     if (hintRectRef) *hintRectRef = hintRect;
 }

README.md

@@ -8,23 +8,64 @@ The project MASShortcut introduces modern API and user interface for recording,
 
 I hope, it is really easy:
 
-	// Drop a custom view into XIB and set its class to MASShortcutView
-	@property (nonatomic, weak) IBOutlet MASShortcutView *shortcutView;
+```objective-c
+// Drop a custom view into XIB and set its class to MASShortcutView
+@property (nonatomic, weak) IBOutlet MASShortcutView *shortcutView;
 	
-	// Think up a preference key to store a global shortcut between launches
-	NSString *const kPreferenceGlobalShortcut = @"GlobalShortcut";
+// Think up a preference key to store a global shortcut between launches
+NSString *const kPreferenceGlobalShortcut = @"GlobalShortcut";
 
-	// Assign the preference key and the shortcut view will take care of persistence
-	self.shortcutView.associatedUserDefaultsKey = kPreferenceGlobalShortcut;
+// Assign the preference key and the shortcut view will take care of persistence
+self.shortcutView.associatedUserDefaultsKey = kPreferenceGlobalShortcut;
 
-	// Execute your block of code automatically when user triggers a shortcut from preferences
-	[MASShortcut registerGlobalShortcutWithUserDefaultsKey:kPreferenceGlobalShortcut handler:^{
-		
-		// Let me know if you find a better or more convenient API.
-	}];
+// Execute your block of code automatically when user triggers a shortcut from preferences
+[MASShortcut registerGlobalShortcutWithUserDefaultsKey:kPreferenceGlobalShortcut handler:^{
+    // Let me know if you find a better or more convenient API.
+}];
+```
 
 To set an example, I made a  demo project: [MASShortcutDemo](https://github.com/shpakovski/MASShortcutDemo). Enjoy!
 
+#Notifications
+By registering for KVO notifications from `NSUserDefaultsController`, you can get a callback whenever a user changes the shortcut, allowing you to perform any UI updates, or other code handling tasks.
+
+This is just as easy to implement:
+    
+```objective-c
+// Declare an ivar for key path in the user defaults controller
+NSString *_observableKeyPath;
+    
+// Make a global context reference
+void *kGlobalShortcutContext = &kGlobalShortcutContext;
+    
+// Implement when loading view
+_observableKeyPath = [@"values." stringByAppendingString:kPreferenceGlobalShortcut];
+[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:_observableKeyPath
+                                                             options:NSKeyValueObservingOptionInitial
+                                                             context:kGlobalShortcutContext];
+
+// Capture the KVO change and do something
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)obj
+                        change:(NSDictionary *)change context:(void *)ctx
+{
+    if (ctx == kGlobalShortcutContext) {
+        NSLog(@"Shortcut has changed");
+    }
+    else {
+        [super observeValueForKeyPath:keyPath ofObject:obj change:change context:ctx];
+    }
+}
+
+// Do not forget to remove the observer
+[[NSUserDefaultsController sharedUserDefaultsController] removeObserver:self
+                                                             forKeyPath:_observableKeyPath
+                                                                context:kGlobalShortcutContext];
+```
+
+# Non-ARC Version
+
+If you like retain/release, please check out these forks: [heardrwt/MASShortcut](https://github.com/heardrwt/MASShortcut) and [chendo/MASShortcut](https://github.com/chendo/MASShortcut). However, the preferred way is to enable the `-fobjc-arc` in Xcode source options.
+
 # Copyright
 
-MASShortcut is licensed under the BSD license.
+MASShortcut is licensed under the 2-clause BSD license.