点语法的知识点

Posted 2020-06-26 高晓牛

今天脑子发晕,有个效果一直没有出来 看了半天代码觉得没什么问题 逻辑什么的都是对的啊  然后  在快要崩溃的时候  我发现原来是点语法的错误:

之前错误的写法:

- (void)setSelected:(BOOL)selected

{

    if (selected == YES) {

        

        _selectedIcon.hidden = NO;

    }else{

        _selectedIcon.hidden = YES;

    }

    [super setSelected:selected];

}

 

正确的写法:

- (void)setSelected:(BOOL)selected

{

    if (selected == YES) {

        

        self.electedIcon.hidden = NO;

    }else{

        self.selectedIcon.hidden = YES;

    }

    [super setSelected:selected];

}

 

//懒加载

 

- (UIImageView *)selectedIcon
{
    if (_selectedIcon == nil) {
        
        _selectedIcon = [[UIImageView alloc]initWithFrame:CGRectMake((self.width-55*[UIScreen mainScreen].bounds.size.width/375)/2, (self.height-55*[UIScreen mainScreen].bounds.size.width/375)/2-20, 55*[UIScreen mainScreen].bounds.size.width/375, 55*[UIScreen mainScreen].bounds.size.width/375)];
        _selectedIcon.clipsToBounds = YES;
        _selectedIcon.layer.cornerRadius = 55*([UIScreen mainScreen].bounds.size.width/375)/2;
        _selectedIcon.backgroundColor = [UIColor colorWithWhite:0 alpha:0.7];
        _selectedIcon.contentMode = UIViewContentModeCenter;
        _selectedIcon.image = [UIImage imageNamed:@"interest_page_selected_icon"];
        _selectedIcon.hidden = YES;
        
        [self addSubview:_selectedIcon];
  }
    return _selectedIcon;
}

 

看着两个代码作用是一样的 但是涉及到点语法  所以差别挺大的:点语法的本质是调用get方法和set方法。同时点语法会调用懒加载 下划线的方法不会!!

三四个小时的时间都在找问题所在  这是个很小的点 很容易忽略 同时也是很重要的一个点  希望不要再犯类似错误!!!!