我们所要解决的问题如题目所示：ios中，长按Webview中的图片，将图片保存到本地相册。
解决方案：对load的html网页，执行js注入，通过在webview中执行js代码，来响应点击事件，通过js代码来模拟长按事件。发现图片的位置，获得图片的url链接，通过此链接获得图片，将此图片保存到本地相册。
js注入代码：
static NSString* const kTouchJavaScriptString=
@"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\";};";
这段js的作用主要用于响应touch事件，以及获得点击的坐标位置，
在webview加载完成之后，将此段js代码注入，源码如下：
-(void)webViewDidFinishLoad:(UIWebView *)webView {
[self.getWebView stringByEvaluatingJavaScriptFromString:kTouchJavaScriptString];
}
js执行代码：
-(BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)_request navigationType:(UIWebViewNavigationType)navigationType {
NSString *requestString = ［_request URL] absoluteString];
NSArray *components = [requestString componentsSeparatedByString:@":"];
if ([components count] > 1 && [(NSString *)[components objectAtIndex:0]
isEqualToString:@"myweb"]) {
if([(NSString *)[components objectAtIndex:1] isEqualToString:@"touch"])
{
//NSLog(@"you are touching!");
//NSTimeInterval delaytime = Delaytime;
if ([(NSString *)[components objectAtIndex:2] isEqualToString:@"start"])
{
/*
@需延时判断是否响应页面内的js...
*/
_gesState = GESTURE_STATE_START;
NSLog(@"touch start!");
float ptX = ［components objectAtIndex:3]floatValue];
float ptY = ［components objectAtIndex:4]floatValue];
NSLog(@"touch point (%f, %f)", ptX, ptY);
NSString *js = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).tagName", ptX, ptY];
NSString * tagName = [self.getWebView stringByEvaluatingJavaScriptFromString:js];
_imgURL = nil;
if ([tagName isEqualToString:@"IMG"]) {
_imgURL = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).src", ptX, ptY];
}
if (_imgURL) {
_timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(handleLongTouch) userInfo:nil repeats:NO];
}
}
else if ([(NSString *)[components objectAtIndex:2] isEqualToString:@"move"])
{
//**如果touch动作是滑动，则取消hanleLongTouch动作**//
_gesState = GESTURE_STATE_MOVE;
NSLog(@"you are move");
}
}
else if ([(NSString*)[components objectAtIndex:2]isEqualToString:@"end"]) {
[_timer invalidate];
_timer = nil;
_gesState = GESTURE_STATE_END;
NSLog(@"touch end");
}
}
return NO;
}
return YES;
}
如果点击的是图片，并且按住的时间超过1s，执行handleLongTouch函数，处理图片的保存操作。
- (void)handleLongTouch {
NSLog(@"%@", _imgURL);
if (_imgURL && _gesState == GESTURE_STATE_START) {
UIActionSheet* sheet = ［UIActionSheet alloc]initWithTitle:nil delegate:self cancelButtonTitle:@"取消" destructiveButtonTitle:nil otherButtonTitles:@"保存图片", nil];
sheet.cancelButtonIndex = sheet.numberOfButtons - 1;
[sheet showInView:[UIApplication sharedApplication].keyWindow];
}
}
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
if (actionSheet.numberOfButtons - 1 == buttonIndex) {
return;
}
NSString* title = [actionSheet buttonTitleAtIndex:buttonIndex];
if ([title isEqualToString:@"保存图片"]) {
if (_imgURL) {
NSLog(@"imgurl = %@", _imgURL);
}
NSString *urlToSave = [self.getWebView stringByEvaluatingJavaScriptFromString:_imgURL];
NSLog(@"image url=%@", urlToSave);
NSData* data = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlToSave］;
UIImage* image = [UIImage imageWithData:data];
//UIImageWriteToSavedPhotosAlbum(image, nil, nil,nil);
UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}
}
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError*)error contextInfo:(void*)contextInfo
{
if (error){
NSLog(@"Error");
[self showAlert:SNS_IMAGE_HINT_SAVE_FAILE];
}else {
NSLog(@"OK");
[self showAlert:SNS_IMAGE_HINT_SAVE_SUCCE];
}
}