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April 28, 2012 19:18
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Invokes a block when an observed KVO property changes
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// Copyright (C) 2012 Kristopher Johnson | |
// | |
// Permission is hereby granted, free of charge, to any person obtaining a copy | |
// of this software and associated documentation files (the "Software"), to deal | |
// in the Software without restriction, including without limitation the rights | |
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
// copies of the Software, and to permit persons to whom the Software is | |
// furnished to do so, subject to the following conditions: | |
// | |
// The above copyright notice and this permission notice shall be included in | |
// all copies or substantial portions of the Software. | |
// | |
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
// THE SOFTWARE. | |
#import <Foundation/Foundation.h> | |
typedef void (^KJPropertyChangeBlock)(id newValue); | |
// Object that invokes a block when a specified property is changed for an observed object | |
@interface KJPropertyObserver : NSObject | |
@property (nonatomic, readonly) NSObject *subject; | |
@property (nonatomic, readonly, copy) NSString *keyPath; | |
@property (nonatomic, readonly, copy) KJPropertyChangeBlock changeBlock; | |
// Return an observer for the specified key path on the specified object | |
+ (KJPropertyObserver *)observerForKeyPath:(NSString *)keyPath ofSubject:(NSObject *)subject onChange:(KJPropertyChangeBlock)changeBlock; | |
// Initialize observation for the specified key path on the specified object | |
- (id)initObservingKeyPath:(NSString *)keyPath ofSubject:(NSObject *)subject onChange:(KJPropertyChangeBlock)changeBlock; | |
@end |
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// Copyright (C) 2012 Kristopher Johnson | |
// | |
// Permission is hereby granted, free of charge, to any person obtaining a copy | |
// of this software and associated documentation files (the "Software"), to deal | |
// in the Software without restriction, including without limitation the rights | |
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
// copies of the Software, and to permit persons to whom the Software is | |
// furnished to do so, subject to the following conditions: | |
// | |
// The above copyright notice and this permission notice shall be included in | |
// all copies or substantial portions of the Software. | |
// | |
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
// THE SOFTWARE. | |
#import "PropertyObserver.h" | |
@interface KJPropertyObserver () | |
@property (nonatomic, readwrite) NSObject *subject; | |
@property (nonatomic, copy, readwrite) NSString *keyPath; | |
@property (nonatomic, copy, readwrite) KJPropertyChangeBlock changeBlock; | |
@end | |
@implementation KJPropertyObserver | |
@synthesize subject = _subject; | |
@synthesize keyPath = _keyPath; | |
@synthesize changeBlock = _changeBlock; | |
+ (KJPropertyObserver *)observerForKeyPath:(NSString *)keyPath ofSubject:(NSObject *)subject onChange:(KJPropertyChangeBlock)changeBlock { | |
return [[KJPropertyObserver alloc] initObservingKeyPath:keyPath ofSubject:subject onChange:changeBlock]; | |
} | |
- (id)initObservingKeyPath:(NSString *)keyPath ofSubject:(NSObject *)subject onChange:(KJPropertyChangeBlock)changeBlock { | |
self = [super init]; | |
if (!self) | |
return nil; | |
self.subject = subject; | |
self.keyPath = keyPath; | |
self.changeBlock = changeBlock; | |
[subject addObserver:self | |
forKeyPath:_keyPath | |
options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionInitial) | |
context:nil]; | |
return self; | |
} | |
- (void)dealloc { | |
[_subject removeObserver:self forKeyPath:_keyPath]; | |
} | |
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { | |
if ([keyPath isEqualToString:_keyPath]) { | |
id newValue = [change valueForKey:NSKeyValueChangeNewKey]; | |
_changeBlock(newValue); | |
} | |
} | |
@end |
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