02.7-Block

#import "ViewController.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet UIView *redView;
@property (nonatomic, copy) void(^completionTask)();


@end

@implementation ViewController


- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    
//    [UIView animateWithDuration:0.5 animations:^{
//        self.redView.center = CGPointMake(300, 400);
//    }completion:^(BOOL finished) {
//        
//    }];
    
//    [UIView beginAnimations:nil context:nil];
//    [UIView setAnimationDuration:0.5];
//    [UIView setAnimationDelegate:self];
//    [UIView setAnimationDidStopSelector:@selector(stop)];
//    
//    //动画执行代理
//    self.redView.center = CGPointMake(300, 400);
//    self.redView.bounds = CGRectMake(0, 0, 200, 200);
//    
//    [UIView commitAnimations];
    
    //定义block
    CGFloat duration = 0.5;
    void (^task)() = ^{
        
        self.redView.center = CGPointMake(300, 400);
        self.redView.bounds = CGRectMake(0, 0, 200, 200);
    };
    
    [self myAnimateWithDuration:0.5 animations:^{
        
        self.redView.center = CGPointMake(300, 400);
        self.redView.bounds = CGRectMake(0, 0, 200, 200);
    }completion:^{
        
        NSLog(@"动画完成");
        NSLog(@"动画完成");
        NSLog(@"动画完成");
        
    }];
    
}



- (void)myAnimateWithDuration:(CGFloat)duration  animations:(void(^)())anim completion:(void(^)())completionTask{
    
    self.completionTask = completionTask;
    
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:duration];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(stop)];
    
    //动画执行代理
    anim();
    
    [UIView commitAnimations];
}

//动画完成时调用
- (void)stop {
    
    self.completionTask();
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    /***
     Block的作用:
     Block是一种数据类型,用来保存代码.
     什么时候使用Block:当做参数进行传递时使用Block
     当某一个方法当中, 某一部份代码不确定时, 此部分代码可以通过外界传入.(使用Blcok)
     */
    
    int a = 10;
    CGFloat b = 10.5;
    
//    void(^blockName)() = ^(){
//        
//        NSLog(@"asdfasdf");
//        NSLog(@"asdfasdf");
//        NSLog(@"asdfasdf");
//        NSLog(@"asdfasdf");
//        NSLog(@"asdfasdf");
//        NSLog(@"asdfasdf");
//        
//    };
//    
//    NSLog(@"%d",a);
//    NSLog(@"%f",b);
//    
//   blockName();
    
    //    int(^sum)(int,int) = ^(int a, int b) {
    //        return  a + b;
    //    };
    //
    //    int res = sum(10,20);
    
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

二、在开发中造成循环引用的情况：

**
1.当使用代理时
2.类与类之间的属性互相引用
3.block会对代码中的强指针进行强引用
4.当时有定时器时，注意可能会造成循环引用（消失时一定要关闭定时器）
**