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