Objective c 是否会有保留周期？

下面是一些抽象代码。有基类“BaseClass”和子类“MyClass”

---

MyClass初始化方法中是否有保留周期？

是；这是一个循环

您可以通过将代码粘贴到一个简单的项目中，然后使用Xcode 8的内存图调试器进行检查

复制/粘贴此可编译版本的代码，然后生成并运行。它将永远运行，什么也不做。单击小对象图调试器图标（三个带线的圆圈），它将显示从sub实例通过块返回到自身的强引用

@interface Base:NSObject
@property (nonatomic, copy) dispatch_block_t block;
@end
@interface Sub:Base
@property (strong, nonatomic) NSString *myString;
@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Sub *s = [[Sub alloc] init];
    }
    dispatch_main();
    return 0;
}

@implementation Base
- initBaseClassWithBlock:(dispatch_block_t)block
{
    self = [super init];

    if (self) {
        self.block = block;
    }

    return self;
}
@end


@implementation Sub
- (instancetype)init {
    if (self = [super initBaseClassWithBlock:^{
        NSLog(@"%@", self.myString);
    }]) {
        ;
    }
    return self;
}
@end

@interface Base:NSObject
@property (nonatomic, copy) dispatch_block_t block;
@end
@interface Sub:Base
@property (strong, nonatomic) NSString *myString;
@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Sub *s = [[Sub alloc] init];
    }
    dispatch_main();
    return 0;
}

@implementation Base
- initBaseClassWithBlock:(dispatch_block_t)block
{
    self = [super init];

    if (self) {
        self.block = block;
    }

    return self;
}
@end


@implementation Sub
- (instancetype)init {
    if (self = [super initBaseClassWithBlock:^{
        NSLog(@"%@", self.myString);
    }]) {
        ;
    }
    return self;
}
@end