河南安阳网站建设,网站主要功能,WordPress 视频cdn,简述网站建设优劣的评价标准在一次开发过程中#xff0c;发现带有行间距的富文本计算高度#xff0c;会有不准确的情况#xff0c;富文本内容明明很长#xff0c;但是计算出的高度只有不到20像素#xff0c;导致整个cell的高度计算异常。
需求上是文字固定宽度#xff0c;最多显示3行#xff0c;超…在一次开发过程中发现带有行间距的富文本计算高度会有不准确的情况富文本内容明明很长但是计算出的高度只有不到20像素导致整个cell的高度计算异常。
需求上是文字固定宽度最多显示3行超过3行尾部打点展示。按照需求设置了尾部打点 paraStyle.lineBreakMode .byTruncatingTail 然后计算富文本的大小。
let range NSRange(location: 0, length: introduce.count)
var att NSMutableAttributedString(string: introduce)
let paraStyle NSMutableParagraphStyle()
paraStyle.lineSpacing 4
att.addAttribute(.font, value: UIFont.systemFont(ofSize: 14), range: range)
// 计算内容高度
let screenWidth UIScreen.main.bounds.size.width
let maxSzie CGSizeMake(screenWidth-40, CGFLOAT_MAX)// 换行模式byClipping
paraStyle.lineBreakMode .byTruncatingTail
att.addAttribute(.paragraphStyle, value: paraStyle, range: range)
size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).size
print(使用byTruncatingTail计算size , size)这时候算出来的size高度只有17像素真实显示到屏幕上Label的高度是58像素。导致整体cell的高度计算错误。 后来发现先将换行模式改为paraStyle.lineBreakMode .byWordWrapping 在计算高度是正确的。于是把所有的换行模式都逐个测试看看到底是什么情况。 func getTextAttributed(_ introduce: String) - NSAttributedString {let range NSRange(location: 0, length: introduce.count)var att NSMutableAttributedString(string: introduce)let paraStyle NSMutableParagraphStyle()paraStyle.lineSpacing 4att.addAttribute(.font, value: UIFont.systemFont(ofSize: 14), range: range)// 计算内容高度let screenWidth UIScreen.main.bounds.size.widthlet maxSzie CGSizeMake(screenWidth-40, CGFLOAT_MAX)// 换行模式byWordWrappingparaStyle.lineBreakMode .byWordWrappingatt.addAttribute(.paragraphStyle, value: paraStyle, range: range)var size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).sizeprint(使用byWordWrapping计算size , size)// 换行模式byCharWrappingparaStyle.lineBreakMode .byCharWrappingatt.addAttribute(.paragraphStyle, value: paraStyle, range: range)size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).sizeprint(使用byCharWrapping计算size , size)// 换行模式byClippingparaStyle.lineBreakMode .byClippingatt.addAttribute(.paragraphStyle, value: paraStyle, range: range)size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).sizeprint(使用byClipping计算size , size)// 换行模式byTruncatingHeadparaStyle.lineBreakMode .byTruncatingHeadatt.addAttribute(.paragraphStyle, value: paraStyle, range: range)size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).sizeprint(使用byTruncatingHead计算size , size)// 换行模式byClippingparaStyle.lineBreakMode .byTruncatingTailatt.addAttribute(.paragraphStyle, value: paraStyle, range: range)size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).sizeprint(使用byTruncatingTail计算size , size)// 换行模式byClippingparaStyle.lineBreakMode .byTruncatingMiddleatt.addAttribute(.paragraphStyle, value: paraStyle, range: range)size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).sizeprint(使用byTruncatingMiddle计算size , size)return att
}
测试后发现系统的5个枚举中只有 byWordWrapping和byCharWrapping 计算准确带有截断方式的case计算都是错误的。 case byWordWrapping 0 // Wrap at word boundaries, defaultcase byCharWrapping 1 // Wrap at character boundariescase byClipping 2 // Simply clipcase byTruncatingHead 3 // Truncate at head of line: ...wxyzcase byTruncatingTail 4 // Truncate at tail of line: abcd...case byTruncatingMiddle 5 // Truncate middle of line: ab...yz 好吧系统这个样子我们也没有办法最后采用的方式
先用 byWordWrapping 计算高度 高度计算完成在修改换行模式paraStyle.lineBreakMode .byTruncatingTail 返回富文本
func getTextAttributed(_ introduce: String) - NSAttributedString {let range NSRange(location: 0, length: introduce.count)let att NSMutableAttributedString(string: introduce)let paraStyle NSMutableParagraphStyle()paraStyle.lineSpacing 4att.addAttribute(.font, value: UIFont.systemFont(ofSize: 14), range: range)// 计算内容高度let screenWidth UIScreen.main.bounds.size.widthlet maxSzie CGSizeMake(screenWidth-40, CGFLOAT_MAX)// 换行模式byWordWrappingparaStyle.lineBreakMode .byWordWrappingatt.addAttribute(.paragraphStyle, value: paraStyle, range: range)var size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).sizeprint(使用byWordWrapping计算size , size)// 换行模式byTruncatingTailparaStyle.lineBreakMode .byTruncatingTailatt.addAttribute(.paragraphStyle, value: paraStyle, range: range)// size att.boundingRect(with: maxSzie, options: [.usesLineFragmentOrigin,.usesFontLeading], context: nil).size// print(使用byTruncatingTail计算size , size)return att
}
