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2017-04-05 19:32:11 +00:00
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@@ -54,7 +54,7 @@ CalendarManager<span class="token punctuation">.</span><span class="token functi
<span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">setState<span class="token punctuation">(</span></span><span class="token punctuation">{</span>events<span class="token punctuation">:</span> events<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span></div><p>A native module should invoke its callback exactly once. It&#x27;s okay to store the callback and invoke it later. This pattern is often used to wrap iOS APIs that require delegates - see <a href="https://github.com/facebook/react-native/blob/master/React/Modules/RCTAlertManager.m" target="_blank"><code>RCTAlertManager</code></a> for an example. If the callback is never invoked, some memory is leaked. If both <code>onSuccess</code> and <code>onFail</code> callbacks are passed, you should only invoke one of them.</p><p>If you want to pass error-like objects to JavaScript, use <code>RCTMakeError</code> from <a href="https://github.com/facebook/react-native/blob/master/React/Base/RCTUtils.h" target="_blank"><code>RCTUtils.h</code></a>. Right now this just passes an Error-shaped dictionary to JavaScript, but we would like to automatically generate real JavaScript <code>Error</code> objects in the future.</p><h2><a class="anchor" name="promises"></a>Promises <a class="hash-link" href="docs/native-modules-ios.html#promises">#</a></h2><p>Native modules can also fulfill a promise, which can simplify your code, especially when using ES2016&#x27;s <code>async/await</code> syntax. When the last parameters of a bridged native method are an <code>RCTPromiseResolveBlock</code> and <code>RCTPromiseRejectBlock</code>, its corresponding JS method will return a JS Promise object.</p><p>Refactoring the above code to use a promise instead of callbacks looks like this:</p><div class="prism language-javascript"><span class="token function">RCT_REMAP_METHOD<span class="token punctuation">(</span></span>findEvents<span class="token punctuation">,</span>
resolver<span class="token punctuation">:</span><span class="token punctuation">(</span>RCTPromiseResolveBlock<span class="token punctuation">)</span>resolve
findEventsWithResolver<span class="token punctuation">:</span><span class="token punctuation">(</span>RCTPromiseResolveBlock<span class="token punctuation">)</span>resolve
rejecter<span class="token punctuation">:</span><span class="token punctuation">(</span>RCTPromiseRejectBlock<span class="token punctuation">)</span>reject<span class="token punctuation">)</span>
<span class="token punctuation">{</span>
NSArray <span class="token operator">*</span>events <span class="token operator">=</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>