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Added NSObject+JKSObserving for simple predictable block based KVO
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,37 @@ | ||
| // | ||
| // JKSObserving.h | ||
| // Frames | ||
| // | ||
| // Created by Johan Sørensen on 10/11/12. | ||
| // Copyright (c) 2012 Johan Sørensen. All rights reserved. | ||
| // | ||
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| #import <Foundation/Foundation.h> | ||
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| typedef void(^JKSObservingHandlerBlock)(id observedObject, NSDictionary *change); | ||
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| @interface JKSObserving : NSObject | ||
| @property (strong, readonly) NSString *keyPath; | ||
| @property (weak, readonly) id observable; | ||
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| + (JKSObserving *)observingWithObject:(id)object | ||
| keyPath:(NSString *)keyPath | ||
| options:(NSKeyValueObservingOptions)options | ||
| handler:(JKSObservingHandlerBlock)handlerBlock; | ||
| - (instancetype)initWithObject:(id)object | ||
| keyPath:(NSString *)keyPath | ||
| options:(NSKeyValueObservingOptions)options | ||
| handler:(JKSObservingHandlerBlock)handlerBlock; | ||
| @end | ||
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| @interface NSObject (JKSObservingAdditions) | ||
| /** Adds an observer for the keyPath | ||
| * | ||
| * @discussion The caller is responsible for controlling the lifetime of the observing, eg. deallocate | ||
| * the returned JKSObserving when the observing is no longer needed/wanted | ||
| */ | ||
| - (JKSObserving *)jks_observingForKeyPath:(NSString *)keyPath | ||
| options:(NSKeyValueObservingOptions)options | ||
| handler:(JKSObservingHandlerBlock)handlerBlock; | ||
| @end |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,92 @@ | ||
| // | ||
| // JKSObserving.m | ||
| // Frames | ||
| // | ||
| // Created by Johan Sørensen on 10/11/12. | ||
| // Copyright (c) 2012 Johan Sørensen. All rights reserved. | ||
| // | ||
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| #import "NSObject+JKSObserving.h" | ||
| #import <objc/runtime.h> | ||
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| static void *JKSObservingKVOContext = &JKSObservingKVOContext; | ||
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| @interface JKSObserving () | ||
| @property (copy) JKSObservingHandlerBlock handler; | ||
| @end | ||
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| @implementation JKSObserving | ||
| + (JKSObserving *)observingWithObject:(id)object | ||
| keyPath:(NSString *)keyPath | ||
| options:(NSKeyValueObservingOptions)options | ||
| handler:(JKSObservingHandlerBlock)handlerBlock | ||
| { | ||
| return [[JKSObserving alloc] initWithObject:object keyPath:keyPath options:options handler:handlerBlock]; | ||
| } | ||
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| - (instancetype)initWithObject:(id)object keyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options handler:(JKSObservingHandlerBlock)handlerBlock | ||
| { | ||
| NSParameterAssert(keyPath); | ||
| NSParameterAssert(handlerBlock); | ||
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| if ((self = [super init])) { | ||
| _keyPath = keyPath; | ||
| _handler = [handlerBlock copy]; | ||
| _observable = object; | ||
| [object addObserver:self forKeyPath:keyPath options:options context:JKSObservingKVOContext]; | ||
| } | ||
| return self; | ||
| } | ||
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| - (void)dealloc | ||
| { | ||
| [_observable removeObserver:self forKeyPath:_keyPath context:JKSObservingKVOContext]; | ||
| } | ||
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| - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context | ||
| { | ||
| if (context == JKSObservingKVOContext) { | ||
| self.handler(self.observable, change); | ||
| } else { | ||
| [super observeValueForKeyPath:keyPath ofObject:object change:change context:context]; | ||
| } | ||
| } | ||
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| @end | ||
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| //NSString *const kAssociatedObservingsKey = @"kAssociatedObservingsKey"; | ||
| @implementation NSObject (JKSObservingAdditions) | ||
| - (JKSObserving *)jks_observingForKeyPath:(NSString *)keyPath | ||
| options:(NSKeyValueObservingOptions)options | ||
| handler:(JKSObservingHandlerBlock)handlerBlock | ||
| { | ||
| JKSObserving *observing = [JKSObserving observingWithObject:self keyPath:keyPath options:options handler:handlerBlock]; | ||
| return observing; | ||
| } | ||
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| //- (void)jks_observeKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options handler:(JKSObservingHandlerBlock)handlerBlock | ||
| //{ | ||
| // // TODO: raise if already added? | ||
| // JKSObserving *observer = [JKSObserving observingWithObject:self keyPath:keyPath options:options handler:handlerBlock]; | ||
| // [[self jks_observings] addObject:observer]; | ||
| //} | ||
| // | ||
| //// Big issue: associated objects area cleared after normal dealloc as part of object_dispose() (see WWDC 2011 session 322 (around 37:35)) | ||
| //// Which means -[JKSObserving dealloc] is called too late and the KVO machinery spews a warning to the console | ||
| //- (NSMutableSet *)jks_observings | ||
| //{ | ||
| // NSMutableSet *observings = objc_getAssociatedObject(self, &kAssociatedObservingsKey); | ||
| // | ||
| // if (!observings) { | ||
| // observings = [[NSMutableSet alloc] init]; | ||
| // objc_setAssociatedObject(self, &kAssociatedObservingsKey, observings, OBJC_ASSOCIATION_RETAIN); | ||
| // } | ||
| // | ||
| // return observings; | ||
| //} | ||
| @end |
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