//单例

//.h

+ (Instannce *)shareInstance;

//.m

static 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;

//.m

if ([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