iOS swift-extension类扩展工具

extension String {    

///返回字符串字符长度    

func YhyStingLengthCount() -> Int{ 

       return self.characters.count   

 }   

 ///范围截取字符串 str[0...3]   

 subscript (r: Range) -> String {

get {

let startIndex = self.characters.index(self.startIndex, offsetBy: r.lowerBound)

let endIndex = self.characters.index(self.startIndex, offsetBy: r.upperBound)

return self[(startIndex ..< endIndex)]

}

}

//在字符串中查找另一字符串首次出现的位置

extension String {

//返回第一次出现的指定子字符串在此字符串中的索引

func positionOf(sub:String)->Int {

var pos = -1

if let range = range(of:sub) {

if !range.isEmpty {

pos = characters.distance(from:startIndex, to:range.lowerBound)

}

}

return pos

}

}

///往后截取字符串

func YhySubStringFrom(_ index:Int) -> String {

return self.substring(from: self.characters.index(self.startIndex, offsetBy: index))

}

///往前截取字符串

func YhySubStringTo(_ index:Int) -> String {

return self.substring(to: self.characters.index(self.startIndex, offsetBy: index))

}

}

//根据开始位置和长度截取字符串

extension String {

//根据开始位置和长度截取字符串

func subString(start:Int, length:Int = -1)->String {

var len = length

if len == -1 {

len = characters.count - start

}

let st = characters.index(startIndex, offsetBy:start)

let en = characters.index(st, offsetBy:len)

let range = st ..< en

return substring(with:range)

}

}

/**

*  重设图片大小

*/

extension UIImage {

func YhyReSizeImage(reSize:CGSize)->UIImage {

//UIGraphicsBeginImageContext(reSize);

UIGraphicsBeginImageContextWithOptions(reSize,false,UIScreen.main.scale);

self.draw(in: CGRect(x: 0, y: 0, width: reSize.width, height: reSize.height))

let reSizeImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()!;

UIGraphicsEndImageContext();

return reSizeImage;

}

/**

*  等比率缩放scaleSize一般设置0.5 ， 0.8

*/

func scaleImage(scaleSize:CGFloat)->UIImage {

let reSize = CGSize(width: self.size.width * scaleSize, height: self.size.height * scaleSize)

return YhyReSizeImage(reSize: reSize)

}

}

///获取label文本高度

func contentSize() -> CGSize {

let size:CGSize

let paragraphStyle = NSMutableParagraphStyle()

paragraphStyle.lineBreakMode = .byWordWrapping

paragraphStyle.alignment = self.textAlignment

let attributes = [NSFontAttributeName:self.font,NSParagraphStyleAttributeName:paragraphStyle] as [String : Any]

size = (self.text! as NSString).boundingRect(with: CGSize(width: self.frame.size.width, height: CGFloat(MAXFLOAT)), options: .usesLineFragmentOrigin, attributes: attributes, context: nil).size

return size

}

}