朝花夕拾之UIButton的title和image自定义布局

当需要实现一个自定义布局图片和标题的按钮时候,不知道有多少少年直接布局了UIButton,亦或是自定义一个UIView,然后以空白UIButton、UILabel、UIImageVew作为subViews。

两者其实都一样,因为UIButton的内部subViews中,就已经存在一个UILabel和UIImageView。

不谈论优劣,只记录一下直接布局UIButton的过程。

因为UIButton已经有一个UILabel显示标题,一个ImageView显示图片,所以可以直接布局。但是需要注意下面记录的问题。

首先,对一个UIButton实例button直接设置title(使用setTitle或者setAttributedTitle方法)和image(使用setImage方法),会发现,图片和标题依次紧贴并排居中显示。

然后,修改一下这个button的titleLabel和imageView的frame,会发现,并没有什么作用。

最后,尝试使用方法setTitleEdgeInsets和setImageEdgeInsets,会发现,没有作用或者布局异常。

问题在于:

1.获取titleLabel的frame时候,size始终是(0, 0)

2.修改titleLabel的frame时机不对

将上述修改操作放在方法layoutSubviews中是合适的。

至于创建UIButton的子类重载方法,还是创建分类来swizzle方法都可以。

即使在这个时机,使用setTitleEdgeInsets还是可能会出现文字显示不全的问题。建议直接修改titleLabel的frame。

我采用了创建分类的方案。定义了一个方法,在+load方法中与layoutSubViews交换。

- (void)base_layoutSubviews
{
    [self base_layoutSubviews];
    
    if (self.resetTitleAndImageLayoutBlock) {
        self.resetTitleAndImageLayoutBlock();
    }
}

代码中自定义的block变量,将重置布局代码延迟到此处调用。

以下代码,是我写的UIButton分类中自定义图片和标题布局的主要方法,其中图片位置暂时只自定义了四种:

- (void)resetButtonTitleAndImageLayoutWithMidInset:(CGFloat)midInset imageLocation:(ButtonImageLocation)imageLocation
{
    CGSize titleSize  = [self.titleLabel.attributedText boundingRectWithSize:CGSizeMake(MAXFLOAT, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin context:nil].size;;
    CGSize imageSize = self.imageView.size;
    
    __weak typeof(self) weakSelf = self;
    
    //因为UIButton在layoutSubviews时候,会重置titleLabel的frame,所以需要延迟调用block
    self.resetTitleAndImageLayoutBlock = ^{
        switch (imageLocation) {
            case ButtonImageLocationUp: {
                CGFloat imageOriginX = (weakSelf.width - imageSize.width) / 2.0;
                CGFloat imageOriginY = (weakSelf.height - titleSize.height - midInset - imageSize.height) / 2.0;
                weakSelf.imageEdgeInsets = UIEdgeInsetsMake(imageOriginY, imageOriginX, weakSelf.height - imageOriginY - imageSize.height, imageOriginX);
                
                CGFloat titleOriginX = (weakSelf.width - titleSize.width) / 2.0;
                CGFloat titleOriginY = imageOriginY + imageSize.height + midInset;
                weakSelf.titleEdgeInsets = UIEdgeInsetsMake(titleOriginY, titleOriginX, weakSelf.height - titleOriginY - titleSize.height, titleOriginX);
                break;
            }
            case ButtonImageLocationLeft: {
                CGFloat imageOriginX = (weakSelf.width - imageSize.width - midInset - titleSize.width) / 2.0;
                CGFloat imageOriginY = (weakSelf.height - imageSize.height) /  2.0;
                weakSelf.imageEdgeInsets = UIEdgeInsetsMake(imageOriginY, imageOriginX, imageOriginY, weakSelf.width - imageOriginX - imageSize.width);
                
                
                CGFloat titleOriginX = imageOriginX + imageSize.width + midInset;
                //横向时候,label的frame可以取较大范围
//                CGFloat titleOriginY = (weakSelf.height - titleSize.height) / 2.0;
//                weakSelf.titleLabel.frame = CGRectMake(titleOriginX, titleOriginY, titleSize.width, titleSize.height);
                weakSelf.titleLabel.frame = CGRectMake(titleOriginX, 0, weakSelf.width - titleOriginX, weakSelf.height);
                [weakSelf.titleLabel setTextAlignment:NSTextAlignmentLeft];
                break;
            }
            case ButtonImageLocationDown: {
                CGFloat titleOriginX = (weakSelf.width - titleSize.width) / 2.0;
                CGFloat titleOriginY = (weakSelf.height - titleSize.height - midInset - imageSize.height) / 2.0;
                weakSelf.titleEdgeInsets = UIEdgeInsetsMake(titleOriginY, titleOriginX, weakSelf.height - titleOriginY - titleSize.height, titleOriginX);
                
                CGFloat imageOriginX = (weakSelf.width - imageSize.width) / 2.0;
                CGFloat imageOriginY = titleOriginY + titleSize.height + midInset;
                weakSelf.imageEdgeInsets = UIEdgeInsetsMake(imageOriginY, imageOriginX, weakSelf.height - imageOriginY - imageSize.height, imageOriginX);
                break;
            }
            case ButtonImageLocationRight: {
                CGFloat titleOriginX = (weakSelf.width - imageSize.width - midInset - titleSize.width) / 2.0;
                //横向时候,label的frame可以取较大范围
//                CGFloat titleOriginY = (weakSelf.height - titleSize.height) / 2.0;
//                weakSelf.titleLabel.frame = CGRectMake(titleOriginX, titleOriginY, titleSize.width, titleSize.height);
                weakSelf.titleLabel.frame = CGRectMake(0, 0, titleOriginX + titleSize.width, weakSelf.height);
                [weakSelf.titleLabel setTextAlignment:NSTextAlignmentRight];
                
                CGFloat imageOriginX = titleOriginX + titleSize.width + midInset;
                CGFloat imageOriginY = (weakSelf.height - imageSize.height) /  2.0;
                weakSelf.imageEdgeInsets = UIEdgeInsetsMake(imageOriginY, imageOriginX, imageOriginY, weakSelf.width - imageOriginX - imageSize.width);
                break;
            }
        }
    };
}

完整的代码请参考Base项目中UIButton的分类。

Base项目已更新:https://github.com/ALongWay/base.git

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