add proximity support

this sensor doesn't need to set UpdateInterval.
will fire event when detected changes.
isNear: true or false

Author: zxcpoiu

README.md

@@ -22,7 +22,8 @@ If you get stuck, take a look at [Brent Vatne's blog](http://brentvatne.ca/packa
 var {
     Accelerometer,
     Gyroscope,
-    Magnetometer
+    Magnetometer,
+    Proximity
 } = require('NativeModules');
 var {
   DeviceEventEmitter // will emit events that you can listen to
@@ -72,6 +73,18 @@ Magnetometer.startMagnetometerUpdates(); // you'll start getting AccelerationDat
 Magnetometer.stopMagnetometerUpdates();
 ```
 
+### Proximity
+```js
+// no need to set UpdateInterval, will fire event when detected changes.
+DeviceEventEmitter.addListener('Proximity', function (data) {
+  /**
+  * data.isNear
+  **/
+});
+Proximity.startProximityUpdates(); // you'll start getting Proximity events above
+Proximity.stopProximityUpdates();
+```
+
 # Example
 
 This repo contains an example react-native app to help get you started. [Source code here.](https://github.com/pwmckenna/react-native-motion-manager/tree/master/Example/MotionExample)

RNMotionManager/Proximity.h

@@ -0,0 +1,17 @@
+//
+//  Proximity.h
+//
+//  Created by zxcpoiu.
+//
+
+#import "RCTBridgeModule.h"
+#import <UIKit/UIKit.h>
+
+@interface Proximity : NSObject <RCTBridgeModule> {
+  UIDevice *_currentDevice;
+}
+- (void) getProximityData:(RCTResponseSenderBlock) cb;
+- (void) startProximityUpdates;
+- (void) stopProximityUpdates;
+
+@end

RNMotionManager/Proximity.m

@@ -0,0 +1,76 @@
+//
+//  Proximity.m
+//
+//  Created by zxcpoiu.
+//
+
+#import "RCTBridge.h"
+#import "RCTEventDispatcher.h"
+#import "Proximity.h"
+
+@implementation Proximity
+
+@synthesize bridge = _bridge;
+
+RCT_EXPORT_MODULE();
+
+- (id) init {
+  self = [super init];
+  NSLog(@"Proximity");
+
+  if (self) {
+
+    self->_currentDevice = [UIDevice currentDevice];
+    [self->_currentDevice setProximityMonitoringEnabled:YES];
+
+    if ([self->_currentDevice isProximityMonitoringEnabled] == YES)
+    {
+      NSLog(@"Proximity available");
+    }
+    else
+    {
+      NSLog(@"Proximity not Available!");
+    }
+    [self->_currentDevice setProximityMonitoringEnabled:NO];
+  }
+  return self;
+}
+
+RCT_EXPORT_METHOD(getProximityData:(RCTResponseSenderBlock) cb) {
+  BOOL state = self->_currentDevice.proximityState;
+  
+  NSLog(@"getProximityData: %@", (state) ? @"YES" : @"NO");
+  
+  cb(@[[NSNull null], @{
+             @"isNear" : [NSNumber numberWithBool:state]
+         }]
+     );
+}
+
+RCT_EXPORT_METHOD(startProximityUpdates) {
+  NSLog(@"startProximityUpdates");
+  [self->_currentDevice setProximityMonitoringEnabled:YES];
+  [self->_currentDevice addObserver:self forKeyPath:@"proximityState" options:NSKeyValueObservingOptionNew context:nil];
+}
+
+RCT_EXPORT_METHOD(stopProximityUpdates) {
+  NSLog(@"stopProximityUpdates");
+  [self->_currentDevice setProximityMonitoringEnabled:NO];
+  [self->_currentDevice removeObserver:self forKeyPath:@"proximityState"];
+}
+
+- (void)observeValueForKeyPath:(NSString *)keyPath
+                      ofObject:(id)object
+                        change:(NSDictionary *)change
+                       context:(void *)context
+{
+  if ([keyPath isEqualToString:@"proximityState"]) {
+    BOOL state = self->_currentDevice.proximityState;
+    [self.bridge.eventDispatcher sendDeviceEventWithName:@"Proximity" body:@{
+                                                                               @"isNear" : [NSNumber numberWithBool:state]
+                                                                           }];
+
+  }
+}
+
+@end

index.js

@@ -1,3 +1,3 @@
-var { Accelerometer, Gyroscope, Magnetometer } = require('react-native').NativeModules;
+var { Accelerometer, Gyroscope, Magnetometer, Proximity } = require('react-native').NativeModules;
 
-module.exports = { Accelerometer, Gyroscope, Magnetometer };
+module.exports = { Accelerometer, Gyroscope, Magnetometer, Proximity };