ios - 访问实例变量导致保留周期？

Question

如果我有:

@interface SomeClass() {
    NSObject *_someObject;
}

...

- (void)someMethod {
    [self doSomething:^(NSObject *someOtherObject) {
          _someObject = someOtherObject;
    }];
}
...

自从我们访问该块中的_someObject以来，是否会与self保持一个循环？

Answer 1

在这种情况下，self将被保留，如果您像下面这样访问类变量，它就像:

- (void)someMethod {
    [self doSomething:^(NSObject *someOtherObject) {
          self->_someObject = someOtherObject;
    }];
}

如果创建的块在self之前被销毁，一切都会好的，但是如果block生存的时间更长，则所有其他对self的引用，self将保留在内存中，而block不会释放它。

我建议使用此代码:

@interface SomeClass()     

@property (nonatomic, strong)NSObject *someObject;

...

- (void)someMethod {
    __weak SomeClass *weak_self = self;
    [self doSomething:^(NSObject *someOtherObject) {
          weak_self.someObject = someOtherObject;
    }];
}
...

要么

@interface SomeClass() {
    NSObject *_someObject;
}

...

- (void)someMethod {
    __weak SomeClass *weak_self = self;
    [self doSomething:^(NSObject *someOtherObject) {
          __strong SomeClass *strong_self = weak_self;
          strong_self->_someObject = someOtherObject;
    }];
}
...