爲什麼物體不能被釋放？

Question

我有一個塊保留週期問題。

1.查看演示，redView是一個本地var，只是一種「UIView」，當我彈出secondVC時，但是secondVC和redView不能被釋放。爲什麼？

@interface RedView : UIView 
@property(nonatomic,copy) void (^redViewBlock)(); 
@end 

---

@implementation SecondVC 

- (void)viewDidLoad { 
[super viewDidLoad]; 
self.view.backgroundColor = [UIColor whiteColor]; 

RedView *redView = [[RedView alloc]initWithFrame:CGRectMake(40, 40, 40, 40)]; 
[redView setRedViewBlock:^{ 
    [self aSecondViewFunc]; 
}]; 
[self.view addSubview:redView]; 

} 

-(void)aSecondViewFunc 
{ 
} 

2.I添加綠景secondVC和redView之間，綠景是一個全局變量，當我彈出secondVC，綠景和redView不能老是被釋放，但secondVC可以釋放。爲什麼？

@interface SecondVC() 

@property(nonatomic,strong)GreenView *greenView; 
@end 

@implementation SecondVC 

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    self.view.backgroundColor = [UIColor whiteColor]; 
    self.greenView = [[GreenView alloc]initWithFrame:CGRectMake(200, 200, 200, 200)]; 
    [self.view addSubview:self.greenView]; 
} 

---

@implementation GreenView 

-(instancetype)initWithFrame:(CGRect)frame 
{ 
    if (self = [super initWithFrame:frame]) { 
    self.backgroundColor = [UIColor greenColor]; 
    RedView *redView = [[RedView alloc]initWithFrame:CGRectMake(0, 0, 40, 40)]; 
    [redView setRedViewBlock:^{ 
     [self justAFunc]; 
    }]; 
    [self addSubview:redView]; 

    } 
    return self; 
} 

Answer 1

由於redView具有參照SecondVC和SecondVC具有參照redView。你應該做weakSelf：

__weak typeof(self) weakSelf = self; 
RedView *redView = [[RedView alloc]initWithFrame:CGRectMake(40, 40, 40, 40)]; 
[redView setRedViewBlock:^{ 
    [weakSelf aSecondViewFunc]; 
}]; 
[self.view addSubview:redView];