在Objective-C块中使用typeof(self)来声明一个强引用

使用weakSelf / strongSelf模式来避免在块中创建保留周期,此代码非常常见：

typeof(self) __weak weakSelf = self;
void (^block)() = ^{
    typeof(weakSelf) strongSelf = weakSelf;
    // ...more code...
};

问题是,将第二种类型(weakSelf)更改为typeof(self)会导致在块中捕获self吗？

例如：

typeof(self) __weak weakSelf = self;
void (^block)() = ^{
    typeof(self) strongSelf = weakSelf; // does using typeof(self) here end up capturing self?
    // ...more code...
};

如果没有捕获自我,是否有任何理由偏爱这种或那种方式？

#import <Foundation/Foundation.h>

int main(int argc,char *argv[]) {
  @autoreleasepool {
    NSObject *o = [NSObject new];

    __weak typeof(o) weakO = o;
    void(^b)() = ^{
      __strong typeof(o) strongO = weakO;
      NSLog(@"o: %@",strongO);
    };

    o = nil;
    b();
    /* outputs:
      2015-05-15 16:52:09.225 Untitled[28092:2051417] o: (null)
     */
  }
}