Question

您好我正在使用以下代码为Tableview使用NSURLConnection SendAsynchronousRequest调用加载图像，但它崩溃了IOS 4.3但相同的代码适用于IOS 5.

所以任何人都可以告诉我，我必须为IOS 4.3提供哪些支持

我已经通过以下链接，但没有任何对我有用。

NSURLConnection sendAsynchronousRequest:queue:completionHandler not working in iOS 4.3

有一个名为

的课程

imagefetcher.h

- (void)fetchImageForURL:(NSURL *)url atIndexPath:(NSIndexPath *)indexPath inTableView:(UITableView *)table;

imagefetcher.m

- (void)fetchImageForURL:(NSURL *)url atIndexPath:(NSIndexPath *)indexPath inTableView:(UITableView *)table {

// NOTE: url is just relative

// There is an issue on iOS 5 that causes the memory capacity to be set to 0 whenever a UIWebView is
// used for the first time. This will correct that issue.
NSLog(@"in fetchImageForURL %@",url);
if([[NSURLCache sharedURLCache] memoryCapacity] != URLMemoryCachSize)
{
    [[NSURLCache sharedURLCache] setMemoryCapacity:URLMemoryCachSize];
}

NSURLRequest *request = [NSURLRequest requestWithURL:url
                                         cachePolicy:NSURLRequestUseProtocolCachePolicy
                                     timeoutInterval:30.0f];


NSCachedURLResponse *cachedResponse = [[NSURLCache sharedURLCache] cachedResponseForRequest:request];
if (cachedResponse)
{
    NSData *data = [cachedResponse data];
    NSLog(@"from cache");
    [self postImageCallbackWithTableView:table atIndexPath:indexPath forURL:url withImageData:data];
}
else
    {
returningResponse:&response error:&error];
//        NSLog(@"loading synchronously");
        [NSURLConnection sendAsynchronousRequest:request
                                           queue:fetcherQueue
                               completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {

                                   [self postImageCallbackWithTableView:table atIndexPath:indexPath forURL:url withImageData:data];

                               }];
//        [self postImageCallbackWithTableView:table atIndexPath:indexPath forURL:url withImageData:data];
    }
}

在tableview控制器中我正在调用follwing方法，但是对于IOS 4.3来说它是crsahes，但对IOS 5来说同样适用

tableviewcontroller.m

-viewdidload()
{

     [NSURLConnection sendAsynchronousRequest:request queue:fetcherQueue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
                            //[self postImageCallbackWithTableView:table atIndexPath:indexPath forURL:url withImageData:data];
                      UIImage *image = [UIImage imageWithData:data];
                        [self.images setObject:image forKey:index];
                        [table1 beginUpdates];
                        [table1 reloadRowsAtIndexPaths:@[index] withRowAnimation:UITableViewRowAnimationNone];
                        [table1 endUpdates];
                    }];
                }

Answer 1

如果您sendAsynchronousRequest查看sendAsynchronousRequest，则需要iOS 5.如果您需要支持iOS 4.3，则必须使用the documentation或connectionWithRequest:delegate:然后实现initWithRequest:delegate:方法（虽然更多的工作，但提供其他优势，例如能够监控进度或在需要时取消请求）。

或者，正如NSURLConnectionDataDelegate提供的答案所示，编写自己的方法，提供sendSynchronousRequest功能但实际上调用sendAsynchronousRequest。

或者，只需用[NSURLConnection sendAsynchronousRequest:request queue:fetcherQueue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) { // do something with `data`, `error`, and `response` }];替换您的通话：

sendSynchronousRequest

通过调用NSOperationQueue，您将在某个@property (nonatomic, retain) NSOperationQueue *networkQueue;队列中执行此操作。因此，首先，为操作队列定义一个属性：

viewDidLoad

然后将其初始化，例如在self.networkQueue = [[NSOperationQueue alloc] init]; self.networkQueue.name = @"com.domain.app.networkqueue"; self.networkQueue.maxConcurrentOperationCount = 4;：

中

sendSynchronousRequest

然后您可以使用该网络操作队列来调用[self.networkQueue addOperationWithBlock:^{ NSURLResponse *response = nil; NSError *error = nil; NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; // assuming you want to interact with your UI and or synchronize changes to your model, dispatch this final processing back to the main queue [[NSOperationQueue mainQueue] addOperationWithBlock:^{ // do something with `data`, `error`, and `response` }]; }];：

sendAsynchronousRequest

最重要的是，只需使用iOS 4.3中提供的方法（例如sendSynchronousRequest）替换您对{{1}}的来电。

NSURLConnection sendAsynchronousRequest用于ios 4中的图像崩溃

1 个答案: