Swift版本UIWebView长按保存图片

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

效果图



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

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

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
}
}