Objective c WebView内存管理

我正在开发的一个应用程序保留了几个web视图，这些视图用于为围绕应用程序的某些活动提供嵌入式web浏览体验。我遇到的问题是，在打开几个小时和大量使用视图之后，视图开始积累内存。我对Objective-C中内存管理的理解是，一旦对象被完全释放（retaincount=0）并被释放，整个应用程序使用的内存量就会下降。这似乎不适用于我的情况

[webviewObject release];
webviewObject = nil;

webviewObject = [[self createNewViewWithName:name] retain];

---

以上是我正在使用的代码。我试着释放内存，不创建新实例，但没有成功。内存使用量只是继续增长，根据仪器，对象被完全释放。我错过什么了吗？应用程序是否可以缓存一些内容？

我的一个应用程序在web视图中遇到类似问题。iphone SDK中的web视图似乎存在内存泄漏。我的应用程序在web视图中出现大文本和其他一些问题时崩溃。帮助我防止内存泄漏。我希望这对你也有用

以下是该链接中的说明：

防止与UIWebView相关的内存泄漏可能很困难。苹果的 关于这一主题的文献很少，也不直接， 仅仅是因为UIWebView是一个复杂的beast，具有许多底层功能 在中使用的类。此Objective-C类别表示一个集合 收集的想法和理论（思考魔法而非科学…） 来自各种网络博客和关于这个主题的讨论。更多 Objective-C内存管理思想，请查看WIJL:IOS内存 管理层。使用类别很简单：

下载代码：UIWebView+Clean.zip

将UIWebView+Clean.h和.m文件添加到项目中

在要在中使用类别的任何文件中导入

UIWebView+Clean.h

在要取消分配UIWebView的任何位置使用

cleanForDealloc

方法：

这是

UIWebView+Clean.h

：

/*

    UIWebView+Clean.h

    A simple category that performs recommended UIWebView clean before dealloc

    Created by Jason Baker (jason@onejasonforsale.com) for TumbleOn on 3/18/12.

    Copyright (c) 2012, Pocket Sized Giraffe, LLC
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this
    list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
    ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    The views and conclusions contained in the software and documentation are those
    of the authors and should not be interpreted as representing official policies,
    either expressed or implied.

 */

#import <Foundation/Foundation.h>

@interface UIWebView (clean)

// performs various cleanup activities recommended for UIWebView before dealloc.
// see comments in implementation for usage examples
- (void) cleanForDealloc;

@end

---

你需要展示“createNewViewWithName:”看起来像什么，我想。是的，看起来他有点过度保留。我不确定createNewViewWithName是否返回自动删除的对象

/*

    UIWebView+Clean.h

    A simple category that performs recommended UIWebView clean before dealloc

    Created by Jason Baker (jason@onejasonforsale.com) for TumbleOn on 3/18/12.

    Copyright (c) 2012, Pocket Sized Giraffe, LLC
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this
    list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
    and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
    ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    The views and conclusions contained in the software and documentation are those
    of the authors and should not be interpreted as representing official policies,
    either expressed or implied.

 */

#import <Foundation/Foundation.h>

@interface UIWebView (clean)

// performs various cleanup activities recommended for UIWebView before dealloc.
// see comments in implementation for usage examples
- (void) cleanForDealloc;

@end

/*

 UIWebView+Clean.h

 A simple category that performs recommended UIWebView clean before dealloc

 Created by Jason Baker (jason@onejasonforsale.com) for TumbleOn on 3/18/12.

 Copyright (c) 2012, Pocket Sized Giraffe, LLC
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:

 1. Redistributions of source code must retain the above copyright notice, this
 list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright notice,
 this list of conditions and the following disclaimer in the documentation
 and/or other materials provided with the distribution.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 The views and conclusions contained in the software and documentation are those
 of the authors and should not be interpreted as representing official policies,
 either expressed or implied.

 */

#import "UIWebView+Clean.h"

@implementation UIWebView (clean)

/*

 Using this Category is easy, simply add this to the top of your file where
 you have a UIWebView:

 #import "UIWebView+Clean.h"

 Then, any time you want to throw away or deallocate a UIWebView instance, do
 the following before you throw it away:

 [self.webView cleanForDealloc];
 self.webView = nil;

 If you still have leak issues, read the notes at the bottom of this class,
 they  may help you.

 */


- (void) cleanForDealloc
{
    /*

     There are several theories and rumors about UIWebView memory leaks, and how
     to properly handle cleaning a UIWebView instance up before deallocation. This
     method implements several of those recommendations.

     #1: Various developers believe UIWebView may not properly throw away child
     objects & views without forcing the UIWebView to load empty content before
     dealloc.

     Source: http://stackoverflow.com/questions/648396/does-uiwebview-leak-memory

     */        
    [self loadHTMLString:@"" baseURL:nil];

    /*

     #2: Others claim that UIWebView's will leak if they are loading content
     during dealloc.

     Source: http://stackoverflow.com/questions/6124020/uiwebview-leaking

     */
    [self stopLoading];

    /*

     #3: Apple recommends setting the delegate to nil before deallocation:
     "Important: Before releasing an instance of UIWebView for which you have set
     a delegate, you must first set the UIWebView delegate property to nil before
     disposing of the UIWebView instance. This can be done, for example, in the
     dealloc method where you dispose of the UIWebView."

     Source: UIWebViewDelegate class reference    

     */
    self.delegate = nil;


    /*

     #4: If you're creating multiple child views for any given view, and you're
     trying to deallocate an old child, that child is pointed to by the parent
     view, and won't actually deallocate until that parent view dissapears. This
     call below ensures that you are not creating many child views that will hang
     around until the parent view is deallocated.
     */

    [self removeFromSuperview];

    /*

     Further Help with UIWebView leak problems:

     #1: Consider implementing the following in your UIWebViewDelegate:

     - (void) webViewDidFinishLoad:(UIWebView *)webView
     {
        //source: http://blog.techno-barje.fr/post/2010/10/04/UIWebView-secrets-part1-memory-leaks-on-xmlhttprequest/
        [[NSUserDefaults standardUserDefaults] setInteger:0 forKey:@"WebKitCacheModelPreferenceKey"];
     }

     #2: If you can, avoid returning NO in your UIWebViewDelegate here:

     - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
     {
        //this source says don't do this: http://stackoverflow.com/questions/6421813/lots-of-uiwebview-memory-leaks
        //return NO;
        return YES;
     }

     #3: Some leaks appear to be fixed in IOS 4.1
     Source: http://stackoverflow.com/questions/3857519/memory-leak-while-using-uiwebview-load-request-in-ios4-0

     #4: When you create your UIWebImageView, disable link detection if possible:        

     webView.dataDetectorTypes = UIDataDetectorTypeNone;

     (This is also the "Detect Links" checkbox on a UIWebView in Interfacte Builder.)

     Sources:
     http://www.iphonedevsdk.com/forum/iphone-sdk-development/46260-how-free-memory-after-uiwebview.html
     http://www.iphonedevsdk.com/forum/iphone-sdk-development/29795-uiwebview-how-do-i-stop-detecting-links.html
     http://blog.techno-barje.fr/post/2010/10/04/UIWebView-secrets-part2-leaks-on-release/

     #5: Consider cleaning the NSURLCache every so often:

     [[NSURLCache sharedURLCache] removeAllCachedResponses];
     [[NSURLCache sharedURLCache] setDiskCapacity:0];
     [[NSURLCache sharedURLCache] setMemoryCapacity:0];

     Source: http://blog.techno-barje.fr/post/2010/10/04/UIWebView-secrets-part2-leaks-on-release/

     Be careful with this, as it may kill cache objects for currently executing URL
     requests for your application, if you can't cleanly clear the whole cache in
     your app in some place where you expect zero URLRequest to be executing, use
     the following instead after you are done with each request (note that you won't
     be able to do this w/ UIWebView's internal request objects..):

     [[NSURLCache sharedURLCache] removeCachedResponseForRequest:request];

     Source: http://stackoverflow.com/questions/6542114/clearing-a-webviews-cache-for-local-files  

     */
}

@end