键盘输入模式获取和语言获取

//键盘输入模式获取
        let lang = textFeild.textInputMode?.primaryLanguage

获取输入框中的高亮部分

 let markedRange = textFeild.markedTextRange

截取到指定位置的字符串

 newText?.substring(to: (newText?.index((newText?.startIndex)!, offsetBy:maxLen))!)

获取image的宽度
OC

CGFloat imageWidth = CGImageGetWidth([_leftLogPicture.image CGImage]);

Swift

let imageWidth = (leftLogPicture?.image?.cgImage)!.width