Swift版本UIWebView长按保存图片

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起因

最近需要做个IOS的壳子，用到长按保存图片的功能，发现百度出来的全是OC语法的例子，很多都不是全面，只能自己写一份Swift版本的，图片下面附上Github地址

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效果图

 

Github地址：https://github.com/goyuanfang/SwifLongTouchSavePic

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原理

UIWebView中 

func webViewDidFinishLoad(webView: UIWebView) 

加载完URL后注入监听手机触摸屏幕的js脚本：

document.ontouchstart=function(event){
  x=event.targetTouches[0].clientX;
  y=event.targetTouches[0].clientY;
  document.location="myweb:touch:start:"+x+":"+y;
};
document.ontouchmove=function(event){
  x=event.targetTouches[0].clientX;
  y=event.targetTouches[0].clientY;
  document.location="myweb:touch:move:"+x+":"+y;};
document.ontouchcancel=function(event){
  document.location="myweb:touch:cancel";
};
document.ontouchend=function(event){
  document.location="myweb:touch:end";
};

 每次监听到手指移动都会将修改document的页面定向，将参数传递给Swift的

webView(webView: UIWebView, shouldStartLoadWithRequest request: NSURLRequest, navigationType: UIWebViewNavigationType)

捕获到页面定向后分析参数，读取到img的src，弹出保存对话框

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代码

enum TouchState {
    case None
    case Start
    case Move
    case End
    case Cancel
}

//脚本触摸事件
static var touchJSStr:String = "document.ontouchstart=function(event){x=event.targetTouches[0].clientX;y=event.targetTouches[0].clientY;document.location="myweb:touch:start:"+x+":"+y;};document.ontouchmove=function(event){x=event.targetTouches[0].clientX;y=event.targetTouches[0].clientY;document.location="myweb:touch:move:"+x+":"+y;};document.ontouchcancel=function(event){document.location="myweb:touch:cancel";};document.ontouchend=function(event){document.location="myweb:touch:end";};"

static var imgUrl:String = ""//存储当前点击的图片路径
var touchState:TouchState = TouchState.None//设置默认的点击状态为NONE
var timer:NSTimer? = nil//定时器 长按时 定时器启动 执行一次 弹出保存确认

ViewController要继承UIWebViewDelegate,UIActionSheetDelegate

 @IBOutlet weak var webView: UIWebView!
    override func viewDidLoad() {
        super.viewDidLoad()
        webView.delegate = self
        webView.loadRequest(NSURLRequest(URL: NSURL(string: "http://image.baidu.com")!))
 }

func webView(webView: UIWebView, shouldStartLoadWithRequest request: NSURLRequest, navigationType: UIWebViewNavigationType) -> Bool{
        let requestStr:String = request.URL!.absoluteString
        let components = requestStr.componentsSeparatedByString(":")
        if(components.count>1 && components[0] == "myweb"){
            if(components[1] == "touch"){
                if(components[2] == "start"){
                    touchState = TouchState.Start
                    let ptX:Float32 = (components[3] as NSString).floatValue
                    let ptY:Float32 = (components[4] as NSString).floatValue
                    let js:String = "document.elementFromPoint((ptX), (ptY)).tagName"
                    let tagName:String? = webView.stringByEvaluatingJavaScriptFromString(js)
                    if(tagName!.uppercaseString == "IMG")
                    {
                        let srcJS:String = "document.elementFromPoint((ptX), (ptY)).src"
                        ViewController.imgUrl = srcJS
                        if(ViewController.imgUrl != ""){
                            timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "handleLongTouch", userInfo: nil, repeats: false)
                        }
                    }
                }else if(components[2] == "move"){
                    touchState = TouchState.Move
                    if(timer != nil)
                    {
                        timer!.fire()
                    }
                }
                else if(components[2] == "cancel"){
                    touchState = TouchState.Cancel
                    if(timer != nil)
                    {
                        timer!.fire()
                    }
                }
                else if(components[2] == "end"){
                    touchState = TouchState.End
                    if(timer != nil)
                    {
                        timer!.fire()
                    }
                }
            }
        }
        return true
    }
    
    func webViewDidFinishLoad(webView: UIWebView){
        webView.stringByEvaluatingJavaScriptFromString(ViewController.touchJSStr)//触摸js注册
    }
    //弹出保存对话框
    func handleLongTouch(){
        if(ViewController.imgUrl != "" && touchState == TouchState.Start){
            var sheet:UIActionSheet = UIActionSheet(title: nil, delegate: self, cancelButtonTitle: "取消", destructiveButtonTitle: nil, otherButtonTitles: "保存图片")
            sheet.cancelButtonIndex = sheet.numberOfButtons - 1
            sheet.showInView(UIApplication.sharedApplication().keyWindow!)
        }
    }
    //按钮点击保存 保存图片 需要实现 UIActionSheetDelegate
    func actionSheet(actionSheet: UIActionSheet, clickedButtonAtIndex buttonIndex: Int){
        if(buttonIndex == 1){
            let urlToSave:String? = self.webView.stringByEvaluatingJavaScriptFromString(ViewController.imgUrl)
            let data:NSData? = NSData(contentsOfURL: NSURL(string: urlToSave!)!)
            var image:UIImage? = UIImage(data: data!)
            UIImageWriteToSavedPhotosAlbum(image!, self, "image:didFinishSavingWithError:contextInfo:", nil)
        }
    }
    
    func image(image: UIImage, didFinishSavingWithError: NSError?, contextInfo: AnyObject) {
        if didFinishSavingWithError != nil {
            return
        }
    }