HXEasyKVO

HXEasyKVO is a lightweight packaging KVO by making callbacks using Block and SEL. The observer will be automatically removed when the observer or observed is released. Of course you can manually remove it earlier. You can specify the thread of callback, and it's thread-safe.

Installation

HXEasyKVO is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'HXEasyKVO'

Example:

import the header file

#import "ViewController.h"
#import "NSObject+HXEasyKVO.h"

@interface ViewController ()
{
    dispatch_queue_t _queue;
}
@property (nonatomic) UILabel *label;
@property (nonatomic) NSObject *o1;
@property (nonatomic) NSObject *o2;
@property (nonatomic) NSObject *o3;
@property (nonatomic) NSObject *o4;
@property (nonatomic) NSObject *o5;
@property (nonatomic) NSObject *o6;
@property (nonatomic) NSObject *o7;
@property (nonatomic) NSObject *o8;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    _queue = dispatch_queue_create("test", NULL);
    _label = [UILabel new];
    _label.text = @"old";
    
    _o1 = [NSObject new];
    _o2 = [NSObject new];
    _o3 = [NSObject new];
    _o4 = [NSObject new];
    _o5 = [NSObject new];
    _o6 = [NSObject new];
    _o7 = [NSObject new];
    _o8 = [NSObject new];
    
    [_o1 hx_observe:_label forKeyPath:@"text" newValueChangeBlock:^(id  _Nullable observer, id  _Nonnull object, id newValue) {
        NSAssert([NSThread.currentThread isMainThread], nil);
        NSLog(@"-1- thread - %@, newValue - %@", NSThread.currentThread, newValue);
    }];
    
    [_o2 hx_observe:_label forKeyPath:@"text" queue:_queue newValueChangeBlock:^(id  _Nullable observer, id  _Nonnull object, id newValue) {
        NSAssert(![NSThread.currentThread isMainThread], nil);
        NSAssert([newValue isEqualToString:@"new"], nil);
        NSLog(@"-2- thread - %@, newValue - %@", NSThread.currentThread, newValue);
    }];
    
    [_o3 hx_observe:_label forKeyPath:@"text" oldAndNewValueChangeBlock:^(id  _Nullable observer, id  _Nonnull object, id  _Nonnull oldValue, id  _Nonnull newValue) {
        NSAssert([NSThread.currentThread isMainThread], nil);
        NSLog(@"-3- oldValue - %@, newValue - %@", oldValue, newValue);
    }];
    
    [_o4 hx_observe:_label forKeyPath:@"text" queue:_queue oldAndNewValueChangeBlock:^(id  _Nullable observer, id  _Nonnull object, id  _Nonnull oldValue, id  _Nonnull newValue) {
        NSAssert(![NSThread.currentThread isMainThread], nil);
        NSLog(@"-4- thread - %@, oldValue - %@, newValue - %@", NSThread.currentThread, oldValue, newValue);
    }];
    
    [_o5 hx_observe:_label forKeyPath:@"text" options:(NSKeyValueObservingOptionNew) context:nil block:^(id  _Nullable observer, id  _Nonnull object, NSDictionary<NSKeyValueChangeKey,id> * _Nonnull change) {
        NSAssert([NSThread.currentThread isMainThread], nil);
        id newValue = change[NSKeyValueChangeNewKey];
        NSLog(@"-5- thread - %@, newValue - %@", NSThread.currentThread, newValue);
    }];
    
    [_o6 hx_observe:_label forKeyPath:@"text" queue:_queue options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:nil block:^(id  _Nullable observer, id  _Nonnull object, NSDictionary<NSKeyValueChangeKey,id> * _Nonnull change) {
        NSAssert(![NSThread.currentThread isMainThread], nil);
        id oldValue = change[NSKeyValueChangeOldKey];
        id newValue = change[NSKeyValueChangeNewKey];
        NSLog(@"-6- thread - %@, oldValue - %@, newValue - %@", NSThread.currentThread, oldValue, newValue);
    }];
    
    [_o7 hx_observe:_label forKeyPath:@"text" options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:nil selector:@selector(KVOInvokeOnMainThreadWithObject:change:)];
    
    [_o8 hx_observe:_label forKeyPath:@"text" queue:_queue options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:nil selector:@selector(KVOInvokeOnConcurrentThreadWithObject:change:)];
    
    // invoke observeValueForKeyPath:ofObject:change:context:
    [self hx_observe:_label forKeyPath:@"text" queue:_queue options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:nil  block:nil];
    
}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    _label.text = @"new";
}

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
    NSAssert([keyPath isEqualToString:@"text"], nil);
    id oldValue = change[NSKeyValueChangeOldKey];
    id newValue = change[NSKeyValueChangeNewKey];
    NSLog(@"-9- thread - %@, oldValue - %@, newValue - %@", NSThread.currentThread, oldValue, newValue);
}


@end

@implementation NSObject (Test)

-(void)KVOInvokeOnMainThreadWithObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change {
    NSAssert([NSThread.currentThread isMainThread], nil);
    id oldValue = change[NSKeyValueChangeOldKey];
    id newValue = change[NSKeyValueChangeNewKey];
    NSLog(@"-7- thread - %@, oldValue - %@, newValue - %@", NSThread.currentThread, oldValue, newValue);
}

-(void)KVOInvokeOnConcurrentThreadWithObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change {
    NSAssert(![NSThread.currentThread isMainThread], nil);
    id oldValue = change[NSKeyValueChangeOldKey];
    id newValue = change[NSKeyValueChangeNewKey];
    NSLog(@"-8- thread - %@, oldValue - %@, newValue - %@", NSThread.currentThread, oldValue, newValue);
}

@end

Author

hins Huang, [email protected]

License

HXEasyKVO is available under the MIT license. See the LICENSE file for more info.