iphone - 如何检测UIWebView的缩放比例

Question

我想在用户放大时增加 UIWebView 的高度(就像 iPhone 中的默认邮件应用程序)。因此，我尝试使用下面的代码在 Web View 中查找 ScrollView ，并添加 UIScrollViewDelegate 以使用 scrollViewDidZoom 检测缩放比例，以在此方法上增加 Web View 的高度。

// MessageAppDelegate.h
@interface MessageAppDelegate : NSObject <UIApplicationDelegate,UIWebViewDelegate,UIScrollViewDelegate> {   
    UIWebView *webview;
    UIScrollView *scrollview;
}


//MessageAppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{

    [self.window makeKeyAndVisible];

    webview = [[UIWebView alloc] initWithFrame:CGRectMake(0, 150, 320, 100)];
    webview.delegate = self;
    webview.scalesPageToFit = YES;
    webview.userInteractionEnabled = YES;

    [webview loadHTMLString:@"<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=6.0 user-scalable=yes\">test test" baseURL:nil];

    [self.window addSubview:webview];

    // Find scrollview in webview
    for (UIView *view in webview.subviews) {
        if ([view isKindOfClass:[UIScrollView class]]) {
            // Get UIScrollView object
            scrollview = (UIScrollView *) view;
            scrollview.delegate = self;
        }
    }

    return YES;
}

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale{
    NSLog(@"scale %f",scale);
}

- (void)scrollViewDidZoom:(UIScrollView *)scrollView{
    NSLog(@"scrollViewDidZoom %f",scrollview.zoomScale);
}

问题是我无法放大/缩小 WebView 但 scrollViewDisEndZooming 方法上的 NSLog 显示

scale 1.0

当我结束缩放时和 scrollViewDidZoom 方法没有显示任何内容。我想检测 webview 的缩放比例以计算其在 scrollViewDidZoom 上的高度。

我做错了什么？请帮忙。

提前致谢。

Answer 1

我已经为你的代码做好了，请进行以下修改:

你只要得到scrollview类点，就可以得到scrollview.contentSize.width，当你放大的时候，它会改变，但是scrollview.zoomScale始终保持1。所以必须使用contensize.width来计算比例。

@interface dictViewController : UIViewController<UIWebViewDelegate,UITextFieldDelegate,UIGestureRecognizerDelegate,UIScrollViewDelegate>{

UIScrollView *scrollview;
......................

//scrollview.delegate = self;

for (UIView *view in webViewM.subviews) {
    if ([view isKindOfClass:[UIScrollView class]]) {
        // Get UIScrollView object
        scrollview = (UIScrollView *) view;
        //scrollview.delegate = self;
    }
}
/*
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale{
//NSLog(@"scale zooming %f",scale);
}

- (void)scrollViewDidZoom:(UIScrollView *)scrollView{
//NSLog(@"scrollViewDidZoom %f",scrollview.zoomScale);
}*/


- (void)swipeRightAction:(id)ignored
{  

 NSLog(@"wid=%f", scrollview.contentSize.width);
 NSLog(@"zoomscale=%f", scrollview.zoomScale);

}