懒加载 warning: could not load any Objective-C class information. This will significantly reduce the qu

错误信息 : warning: could not load any Objective-C class information. This will significantly reduce the quality of type information available.

懒加载的时候: 一定不要用self., 若用 self. 会造成死循环

-(UIButton *)button{    if (!_button) {        _button = [UIButton buttonWithType:UIButtonTypeCustom];        _button.frame = CGRectMake(x, y, with, height);        [self.view addSubview:_button];    }    return _button;}