高性能iOS应用开发 笔记08

Jietu20180904-170843.jpg

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.person = [[Person alloc] init];
    self.person.name = @"Amy";
    
    __weak typeof(self) weakSelf = self;
    
    self.resultLabelMonitor = [ObserverManager addObserverToObject:self.person forKey:@"name" block:^(NSDictionary *changes) {
        typeof(weakSelf) sself = weakSelf;
        
        if(sself)
        {
            sself.resultLabel.text = [changes valueForKey:@"new"];
        }
    }];
    
    self.person.name = @"Mary";
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

- (IBAction)onClickClose:(id)sender
{
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (void)dealloc
{
    NSLog(@"Page5VC dealloc");
}

@interface Person : NSObject

@property (nonatomic, copy) NSString *name;

@end

@interface ObserverManager : NSObject

+ (ObserverObserveeHandle *)addObserverToObject:(NSObject *)obj forKey:(NSString *)keyPath block:(void (^)(NSDictionary *))inputBlock;

@end

+ (ObserverObserveeHandle *)addObserverToObject:(NSObject *)obj forKey:(NSString *)keyPath block:(void (^)(NSDictionary *))inputBlock
{
    MyObserver *observer = [[MyObserver alloc] init];
    observer.block = inputBlock;
    
    [obj addObserver:observer forKeyPath:keyPath options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) context:NULL];
    
    ObserverObserveeHandle *details = [[ObserverObserveeHandle alloc] initWithObserver:observer target:obj keyPath:keyPath];
    
    return details;
}

@interface MyObserver : NSObject

@property (nonatomic, copy) void (^block)(NSDictionary *);

@end

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context
{
    NSLog(@"%@对象的%@属性改变了:%@", object, keyPath, change);
    
    if(self.block)
    {
        self.block(change);
    }
}

- (void)dealloc
{
    NSLog(@"MyObserver dealloc");
}

@interface ObserverObserveeHandle : NSObject

@property (nonatomic, strong) MyObserver *observer;
@property (nonatomic, strong) NSObject *obj;
@property (nonatomic, copy) NSString *keyPath;

- (id)initWithObserver:(MyObserver *)observer target:(NSObject *)obj keyPath:(NSString *)keyPath;

@end

- (id)initWithObserver:(MyObserver *)observer target:(NSObject *)obj keyPath:(NSString *)keyPath
{
    self = [super init];
    
    if(self)
    {
        self.observer = observer;
        self.obj = obj;
        self.keyPath = keyPath;
    }
    
    return self;
}

- (void)removeObserver
{
    [self.obj removeObserver:self.observer forKeyPath:self.keyPath context:nil];
    
    self.observer = nil;
    
    self.obj = nil;
}

- (void)dealloc
{
    NSLog(@"ObserverObserveeHandle dealloc");
    
    [self removeObserver];
}