iOS模仿微信长按识别二维码的多种方式

方式二：识别网页中的二维码

iOS WebView中 长按二维码的识别

思路:

长按webView 的过程中 截屏，再去解析是否有二维码，但是有个缺点 就是 万一截了一个 一半的二维码 那就无解了。

在webview中 注入获取点击图片的JS 获取图片，再解析。缺点：万一图片过大 需要下载，势必会影响用户体验。

@interface CVWebViewController ()<UIGestureRecognizerDelegate>
@property (weak, nonatomic) IBOutlet UIWebView *webView;
@end
@implementation CVWebViewController
- (void)viewDidLoad
{
  [self.webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.easck.com/s?__biz=MzI2ODAzODAzMw==&mid=2650057120&idx=2&sn=c875f7d03ea3823e8dcb3dc4d0cff51d&scene=0#wechat_redirect"]]];
  UILongPressGestureRecognizer *longPressed = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressed:)];
  longPressed.delegate = self;
  [self.webView addGestureRecognizer:longPressed];
}
- (void)longPressed:(UITapGestureRecognizer*)recognizer
{
  if (recognizer.state != UIGestureRecognizerStateBegan) {
    return;
  }
  CGPoint touchPoint = [recognizer locationInView:self.webView];
  NSString *js = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).src", touchPoint.x, touchPoint.y];
  NSString *imageUrl = [self.webView stringByEvaluatingJavaScriptFromString:js];
  if (imageUrl.length == 0) {
    return;
  }
  NSLog(@"image url：%@",imageUrl);
  NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:imageUrl]];
  UIImage *image = [UIImage imageWithData:data];
  if (image) {
    //......
    //save image or Extract QR code
  }
}
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
  return YES;
}