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[操作系统]iOS 之单例,代理,通知,KVO,Block全能解析


//单例//.h+ (Instannce *)shareInstance;//.mstatic Instannce *instance = nil;@implementation Instannce//定义一个创建单例对象的方法+ (Instannce *)shareInstance {  if (instance == nil) {    instance = [[Instannce alloc] init];  }    return instance;}//使用alloc的时候调用的方法instancetype+ (id)allocWithZone:(struct _NSZone *)zone {  if (instance == nil) {    instance = [super allocWithZone:zone];  }   return instance;}- (id)copy {  return self;}- (id)retain {  return self;}- (NSUInteger)retainCount {  //返回无符号最大值  return UINT_MAX;}- (oneway void)release {  //什么也不做}//代理//.h@protocol GetMessageProtocol <NSObject >- (void)getNum:(NSString *)num withPassWord:(NSString *)pass;@end@property (nonatomic,assign) id<GetMessageProtocol> delegate;//.mif ([self.delegate respondsToSelector:@selector(getNum:withPassWord:)]) {    [self.delegate getNum:num.text withPassWord:passWord.text];  }#pragma mark - GetMessageProtocol- (void)getNum:(NSString *)num withPassWord:(NSString *)pass {  }registerCtrl.delegate = self;//通知 注意postNotificationName 必须一致  [[NSNotificationCenter defaultCenter] postNotificationName:NotificationName object:self userInfo:dic]; //dic存放在userinfo中  dic中存放要传过去的值是个字典//接受通知  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(changeAction:) name:NotificationName object:nil];//KVO监听/*KVO观察者方法 keyPath: 监听的属性名 object: 被观察的对象 change: 属性值 context: 上下设备文 */  [registerCtrl addObserver:self forKeyPath:@"属性名称1" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:nil];  [registerCtrl addObserver:self forKeyPath:@"属性名称2" options:NSKeyValueObservingOptionNew context:nil];//触发的事件- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {  //object的值是registerCtrl  if ([keyPath isEqualToString:@"属性名称1"]) {      }else if ([keyPath isEqualToString:@"属性名称2"]) {      } }//.h@property (nonatomic, copy) NSString *属性名称1;@property (nonatomic, copy) NSString *属性名称2;//.m  必须通过setter方法改变值或者KVC//KVO方式//触发的事件[indexCollectionView addObserver:self forKeyPath:@"属性名称" options:NSKeyValueObservingOptionNew context:nil];    [posterCollectionView addObserver:self forKeyPath:@"pathIndex" options:NSKeyValueObservingOptionNew context:nil];- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {  //得到改变后的新值  NSInteger index = [[change objectForKey:@"new"] integerValue];  }}//Block block的返回值 block的名称  block的参数  typedef void(^SucccessBlock)(NSString *); //Block的定义@property(nonatomic,copy)SucccessBlock loginBlock; //block的声明 要用copy防止block的循环引用_freindBlcok(friends); block的调用[[MyXMPPManager shareManager] getFreind:^(NSArray *freinds) {}  //block的赋值 实现