iOS——WKWebView加载网页禁止缩放

设置代理：_webView.scrollView.delegate = self;

实现代理方法：
- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view {
    [scrollView setValue:@(NO) forKeyPath:@"pinchGestureRecognizer.enabled"];
}