boundingRectWithSize

来源：互联网发布：破获网络贩毒编辑：程序博客网时间：2024/05/06 08:56

boundingRectWithSize 的使用, 计算UILable高度, 包含Emoji及多属性string.

iOS的文字高度计算一直是个问题, 苹果也一直在改, 这几天看了一下 boundingRectWithSize 方法.

- (CGRect)boundingRectWithSize:(CGSize)size options:(NSStringDrawingOptions)options context:(NSStringDrawingContext *)context NS_AVAILABLE_IOS(6_0);

踩了几个坑后, 总算找到比较好的使用方法.

参考: http://stackoverflow.com/questions/13621084/boundingrectwithsize-for-nsattributedstring-returning-wrong-size

使用时的注意事项:

1: NSAttributedString 的每个部分都要至少设置两个属性:

NSFontAttributeName

NSForegroundColorAttributeName

2: NSStringDrawingOptions 的值, 在多行的情况下, 至少要有

NSStringDrawingUsesLineFragmentOrigin

NSStringDrawingUsesFontLeading

3: 如果文字中可能会出现emoji表情的话, emoji的高度比文字要高一点点,

我的方便是简单的在高度基础上加了两个像素.

(用CoreText可能会好一些, 但相对复杂.)

附代码:

NSMutableAttributedString *attrStr = [[NSMutableAttributedString alloc] initWithString:fullDescAndTagStr];NSRange allRange = [fullDescAndTagStr rangeOfString:fullDescAndTagStr];[attrStr addAttribute:NSFontAttributeName                value:[UIFont systemFontOfSize:13.0]                range:allRange];[attrStr addAttribute:NSForegroundColorAttributeName                value:[UIColor blackColor]                range:allRange];NSRange destRange = [fullDescAndTagStr rangeOfString:tagStr];[attrStr addAttribute:NSForegroundColorAttributeName                value:HEXCOLOR(0x009cdd)                range:destRange];CGFloat titleHeight;NSStringDrawingOptions options =  NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading;CGRect rect = [attrStr boundingRectWithSize:CGSizeMake(labelWidth, CGFLOAT_MAX)                                    options:options                                    context:nil];titleHeight = ceilf(rect.size.height);return titleHeight+2;  // 加两个像素,防止emoji被切掉.

http://www.csdn123.com/html/topnews201408/92/1692.htm

0 0