Ios: complete iOS vibration pattern supports (js)

Summary:
This is a revised follow up version from #8574 ( originally implemented in `objc` )
This PR change the implementation in JS suggested by javache

**motivation**

To supports vibration pattern like android.

The [iOS vibration implementation link](http://stackoverflow.com/questions/12966467/are-there-apis-for-custom-vibrations-in-ios/13047464#13047464) mentioned by skv-headless at https://github.com/facebook/react-native/pull/6061#discussion_r54062592, which will not be accepted by apple since that implementation uses a private API. Thus, I use pure public API `NSTimer` to implement it.

**Note**

Since vibration time on iOS is not configurable, there are slightly differences with android.
for example:

**Android Usage:**
`Vibration.vibrate([0, 500, 200, 500])`
==> V(0.5s) --wait(0.2s)--> V(0.5s)

`Vibration.vibrate([300, 500, 200, 500])`
==> --wait(0.3s)--> V(0.5s) --wait(0.2s)--> V(0.5s)

**iOS Usage:**
if first argument is 0, it will not be included in pattern array.
( vibration
Closes https://github.com/facebook/react-native/pull/9233

Differential Revision: D3775085

Pulled By: javache

fbshipit-source-id: 370495857d5581399de32d2bed1ea1bcce193e9d

Examples/UIExplorer/js/VibrationExample.js

@@ -30,12 +30,45 @@ var {
   Text,
   TouchableHighlight,
   Vibration,
+  Platform,
 } = ReactNative;
 
 exports.framework = 'React';
 exports.title = 'Vibration';
 exports.description = 'Vibration API';
+
+var pattern, patternLiteral, patternDescription;
+if (Platform.OS === 'android') {
+  pattern = [0, 500, 200, 500];
+  patternLiteral = '[0, 500, 200, 500]';
+  patternDescription = `${patternLiteral}
+arg 0: duration to wait before turning the vibrator on.
+arg with odd: vibration length.
+arg with even: duration to wait before next vibration.
+`;
+} else {
+  pattern = [0, 1000, 2000, 3000];
+  patternLiteral = '[0, 1000, 2000, 3000]';
+  patternDescription = `${patternLiteral}
+vibration length on iOS is fixed.
+pattern controls durations BETWEEN each vibration only.
+
+arg 0: duration to wait before turning the vibrator on.
+subsequent args: duration to wait before next vibrattion.
+`;
+}
+
 exports.examples = [
+  {
+    title: 'Pattern Descriptions',
+    render() {
+      return (
+        <View style={styles.wrapper}>
+          <Text>{patternDescription}</Text>
+        </View>
+      );
+    },
+  },
   {
     title: 'Vibration.vibrate()',
     render() {
@@ -51,12 +84,12 @@ exports.examples = [
     },
   },
   {
-    title: 'Vibration.vibrate([0, 500, 200, 500])',
+    title: `Vibration.vibrate(${patternLiteral})`,
     render() {
       return (
         <TouchableHighlight
           style={styles.wrapper}
-          onPress={() => Vibration.vibrate([0, 500, 200, 500])}>
+          onPress={() => Vibration.vibrate(pattern)}>
           <View style={styles.button}>
             <Text>Vibrate once</Text>
           </View>
@@ -65,12 +98,12 @@ exports.examples = [
     },
   },
   {
-    title: 'Vibration.vibrate([0, 500, 200, 500], true)',
+    title: `Vibration.vibrate(${patternLiteral}, true)`,
     render() {
       return (
         <TouchableHighlight
           style={styles.wrapper}
-          onPress={() => Vibration.vibrate([0, 500, 200, 500], true)}>
+          onPress={() => Vibration.vibrate(pattern, true)}>
           <View style={styles.button}>
             <Text>Vibrate until cancel</Text>
           </View>

Libraries/Vibration/Vibration.js

@@ -20,12 +20,59 @@ var Platform = require('Platform');
  *
  * There will be no effect on devices that do not support Vibration, eg. the simulator.
  *
- * Note for android
+ * **Note for android**
  * add `<uses-permission android:name="android.permission.VIBRATE"/>` to `AndroidManifest.xml`
  *
- * Vibration patterns are currently unsupported.
+ * **Android Usage:**
+ *
+ * [0, 500, 200, 500]
+ * V(0.5s) --wait(0.2s)--> V(0.5s)
+ *
+ * [300, 500, 200, 500]
+ * --wait(0.3s)--> V(0.5s) --wait(0.2s)--> V(0.5s)
+ *
+ * **iOS Usage:**
+ * if first argument is 0, it will not be included in pattern array.
+ *
+ * [0, 1000, 2000, 3000]
+ * V(fixed) --wait(1s)--> V(fixed) --wait(2s)--> V(fixed) --wait(3s)--> V(fixed)
  */
 
+var _vibrating: boolean = false;
+var _id: number = 0; // _id is necessary to prevent race condition.
+
+function vibrateByPattern(pattern: Array<number>, repeat: boolean = false) {
+  if (_vibrating) {
+    return;
+  }
+  _vibrating = true;
+  if (pattern[0] === 0) {
+    RCTVibration.vibrate();
+    pattern = pattern.slice(1);
+  }
+  if (pattern.length === 0) {
+    _vibrating = false;
+    return;
+  }
+  setTimeout(() => vibrateScheduler(++_id, pattern, repeat, 1), pattern[0]);
+}
+
+function vibrateScheduler(id, pattern: Array<number>, repeat: boolean, nextIndex: number) {
+  if (!_vibrating || id !== _id) {
+    return;
+  }
+  RCTVibration.vibrate();
+  if (nextIndex >= pattern.length) {
+    if (repeat) {
+      nextIndex = 0;
+    } else {
+      _vibrating = false;
+      return;
+    }
+  }
+  setTimeout(() => vibrateScheduler(id, pattern, repeat, nextIndex+1), pattern[nextIndex]);
+}
+
 var Vibration = {
   vibrate: function(pattern: number | Array<number> = 400, repeat: boolean = false) {
     if (Platform.OS === 'android') {
@@ -37,10 +84,13 @@ var Vibration = {
         throw new Error('Vibration pattern should be a number or array');
       }
     } else {
+      if (_vibrating) {
+        return;
+      }
       if (typeof pattern === 'number') {
         RCTVibration.vibrate();
       } else if (Array.isArray(pattern)) {
-        console.warn('Vibration patterns are not supported on iOS');
+        vibrateByPattern(pattern, repeat);
       } else {
         throw new Error('Vibration pattern should be a number or array');
       }
@@ -48,12 +98,10 @@ var Vibration = {
   },
   /**
    * Stop vibration
-   *
-   * @platform android
    */
   cancel: function() {
     if (Platform.OS === 'ios') {
-      console.warn('Vibration.cancel is not supported on iOS');
+      _vibrating = false;
     } else {
       RCTVibration.cancel();
     }