如何在目标C中创建网页的缩略图？

Question

我是iOS的新手。在我的项目中，我需要在图像视图中添加网页的缩略图。我为此创建了一个NSObject类。我在该类中启动了Web视图，但它不会调用UIWebView Delegates.I在此处发布了代码。如果任何人有解决方案或库文件进行缩略图处理可能有用。谢谢。

@interface ThumbNail()<UIWebViewDelegate>
{
    UIImageView *thumbNailImageView;
    UIWebView *mockUpWebView;
    UIImage *viewImage;
}
@end

@implementation ThumbNail

-(void)webViewDidFinishLoad:(UIWebView *)webView {
   thumbNailImageView.image = [self captureScreen:webView];
}

-(void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error{
    NSLog(@"Errorrr.............");
}

-(BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest     *)request navigationType:(UIWebViewNavigationType)navigationType {
   NSLog(@"Got it");
   return YES;
}

-(UIImage*)captureScreen:(UIWebView*) viewToCapture{
    CGSize overallSize = CGSizeMake(mockUpWebView.frame.size.width, mockUpWebView.frame.size.width);
    UIGraphicsBeginImageContext(viewToCapture.scrollView.contentSize);
    viewToCapture.bounds = CGRectMake(0, 0, overallSize.width, overallSize.height);
    while (viewToCapture.loading) {
        [NSThread sleepForTimeInterval:0.1];
    } 
    [viewToCapture.layer renderInContext:UIGraphicsGetCurrentContext()];
    viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return viewImage;
}

-(void)getThumbNailForImageView:(UIImageView *)imageView{
    thumbNailImageView = imageView;
    NSString *urlAddress = @"https://in.yahoo.com/?p=us";

    //Create a URL object.
    NSURL *url = [NSURL URLWithString:urlAddress];

    //URL Requst Object
    NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];

    //Load the request in the UIWebView.
    CGRect bounds              = [[UIScreen mainScreen] bounds];
    mockUpWebView              = [[UIWebView alloc]initWithFrame:bounds];
    NSLog(@"bounds = %@",NSStringFromCGRect(bounds));
    mockUpWebView.delegate     = self;
    [mockUpWebView loadRequest:requestObj];
}
@end

我试图通过调用getThumbNailForImageView来获取缩略图。