如何从UIWebview或dealloc UIWebview中删除缓存

问题描述

每次使用 UIWebView 加载新网页时，系统会在短时间内显示之前加载的网页。

如何清除缓存？另一种可能性是dealloc UIWebview 。我试过，但比我的 UIWebView 始终是空。在这种情况下应该如何处理 alloc 和 dealloc ？

我注意到 UIWebView 正在消耗大约10 MB RAM。现在 UIWebView 与 ViewController 一起加载。并且视图是自动释放的，以及 UIWebView 是自动释放的。

pre> - （void）viewWillAppear：（BOOL）animated {
[super viewWillAppear：animated];

CGRect frame = CGRectMake（0，0，320，480）;
self.webView = [[[UIWebView alloc] initWithFrame：frame] autorelease];
self.webView.scalesPageToFit = YES;
[self.view addSubview：self.webView];
}

- （void）viewDidDisappear：（BOOL）animated {
[super viewDidDisappear：animated];

[self.webView removeFromSuperview];
self.webView = nil;
}


解决方案

在 viewWillAppear：上以编程方式创建 UIWebView ，并在上发布viewDidDisappear：，像这样：

   - （void）viewWillAppear：（BOOL）animated {
 [super viewWillAppear ：animated]; 
 
 self.webView = [[[UIWebView alloc] initWithFrame：exampleFrame] autorelease]; 
 self.webView.scalesPageToFit = YES; 
 self.webView.delegate = self; 
 self.webView.autoresizingMask = webViewBed.autoresizingMask; 
 [exampleView addSubview：self.webView]; 
} 
  - （void）viewDidDisappear：（BOOL）animated {
 [super viewDidDisappear：animated]; 
 
 [self.webView removeFromSuperview]; 
 self.webView.delegate = nil; 
 self.webView = nil; 
} 
  

如果你这样做，你的 UIWebView 没有得到释放，你应该检查它的保留计数，并明白谁保留它。

Every time I load a new page with UIWebView the before loaded page is shown for a short time.

How can I clear that cache? Another possibility would be to dealloc UIWebview. I tried that but than my UIWebView is always "empty". How should the alloc and dealloc be done in this case?

I noticed that the UIWebView is consuming about 10 MB RAM. Now the UIWebView is loaded together with the ViewController. And the view is autoreleased as well as the UIWebView is autoreleased. Wouldn't it be better to dealloc the WebView each time?

Solution:

- (void) viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    CGRect frame = CGRectMake(0, 0, 320, 480);
    self.webView = [[[UIWebView alloc]initWithFrame:frame] autorelease];
    self.webView.scalesPageToFit = YES;
    [self.view addSubview:self.webView];
}

- (void) viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];

    [self.webView removeFromSuperview];
    self.webView = nil;
}

解决方案

My solution to this problem was to create the UIWebView programmatically on viewWillAppear: and to release it on viewDidDisappear:, like this:

- (void) viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    self.webView = [[[UIWebView alloc]initWithFrame:exampleFrame] autorelease];
    self.webView.scalesPageToFit = YES;
    self.webView.delegate = self;
    self.webView.autoresizingMask = webViewBed.autoresizingMask;
    [exampleView addSubview:self.webView];
}
- (void) viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];

    [self.webView removeFromSuperview];
    self.webView.delegate = nil;
    self.webView = nil;
}

If you do this and your UIWebView doesn't get released you should check it's retain count and understand who is retaining it.

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