5

我在使用 NSURLConnection 时遇到了一些非常奇怪的问题，所以我希望你能帮助我。

我想做的是使用 NSURLConnection 从给定的 URL 下载一些数据。

我创建了自己的帮助类，它接收数据路径，下载它，并在下载完成时通过委托通知调用者。

这东西在我的装有 iOS 4.3 的 iPhone 上完美运行。但是，在 iOS 5 或 iOS6 上进行测试时，该connection:(NSURLConnection *)connection didReceiveData:(NSData *)data方法从未被调用，我也没有得到想要的结果。

类 .h 文件包含：

#import <Foundation/Foundation.h>

@protocol NIAsyncDownloaderDelegate
@required
- (void) asyncDownloaderDataDownloadComplete:(NSData *)data withError:(bool) error;
@end

@interface NIAsyncImageDownloader : NSObject <NSURLConnectionDataDelegate>
{
    NSURLConnection *theConnection;
    NSMutableData* myData;

    NSURL *downloadURL;

    id delegate;
}

-(id) initWithDataDownloadString:(NSString *) stringAddress;

@property (nonatomic, retain) id delegate;

@end

.m 文件如下所示：

#import "NIAsyncDownloader.h"

@implementation NIAsyncImageDownloader

@synthesize delegate;

-(id) initWithDataDownloadString:(NSString *)stringAddress
{
    if (self = [super init])
    {
        [self loadDataFromURL:[NSURL URLWithString:stringAddress]];
    }
    return self;
}

- (void)loadDataFromURL:(NSURL*)url
{
    NSLog(@"Called: %@", NSStringFromSelector(_cmd));
    downloadURL = url;

    NSURLRequest* request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
    theConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
}

-(void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"Called: %@", NSStringFromSelector(_cmd));
    NSLog(@"The response is: %@, status code %i, url %@", response.description, ((NSHTTPURLResponse*)response).statusCode, ((NSHTTPURLResponse*)response).URL.description);
}

-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    NSLog(@"Called: %@", NSStringFromSelector(_cmd));

    if (myData == nil)
    {
        myData = [[NSMutableData alloc] initWithCapacity:2048];
    }

    [myData appendData:data];
}

//CALLED ON iOS 4.3
- (void)connectionDidFinishLoading:(NSURLConnection*)connection
{
    //so self data now has the complete image
    NSLog(@"Called: %@", NSStringFromSelector(_cmd));
    [self handleDownloadSuccess];
}

//CALLED ON iOS 5, iOS 6
-(void) connectionDidFinishDownloading:(NSURLConnection *)connection destinationURL:(NSURL *)destinationURL
{
    NSLog(@"Called: %@", NSStringFromSelector(_cmd));
    [self handleDownloadSuccess];
}

-(void) handleDownloadSuccess
{    
    NSLog(@"Called: %@", NSStringFromSelector(_cmd));
    [theConnection release];
    theConnection = nil;

    [delegate asyncDownloaderDataDownloadComplete:myData withError:NO];

    [myData release];
    myData = nil;
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"Called: %@", NSStringFromSelector(_cmd));
    [delegate asyncDownloaderDataDownloadComplete:nil withError:YES];
}

@end

以下是一些屏幕截图，向您展示我在说什么：

这就是我在 iOS5 或 iOS6 上运行应用程序时发生的情况，请求会自行初始化，收到响应并connectionDidFinishDownloading:(NSURLConnection *)connection destinationURL:(NSURL *)destinationURL立即 调用ios5 ios6

但是，当我在 iOS 4.3 上运行相同的应用程序时，一切正常，正如您从下面的屏幕截图中看到的那样：

ios4.3 1 iOS4.3 2

我还注意到 iOS 5 和 iOS 6 不像 iOS 4.3 那样调用相同的“完成”方法，但我认为这与我当前的问题没有任何关系。

最后，这里的文档说，从 iOS 4.3 开始，有问题的方法 (connection:didReceiveData) 实际上已被弃用：http: //developer.apple.com/library/ios/#documentation/Foundation/Reference/ NSURLConnectionDelegate_Protocol/DeprecationAppendix/AppendixADeprecatedAPI.html

但是，另一个参考指出它是 NSURLConnectionDataDelegate 协议的一部分，并且从 iOS 2 开始可用：http: //developer.apple.com/library/ios/#documentation/Foundation/Reference/NSURLConnectionDataDelegate_protocol/Reference/Reference.html

XCode 似乎同意它已被弃用：

代码

万一有人想知道我是如何使用下载器的，这真的很简单：

在.h中：

#import <UIKit/UIKit.h>
#import "NIAsyncDownloader.h"

@interface DTViewController : UIViewController <NIAsyncDownloaderDelegate>
{
    NIAsyncImageDownloader *downloader;
}

@end

在 .m 中：

#import "DTViewController.h"

@interface DTViewController ()

@end

@implementation DTViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    downloader = [[NIAsyncImageDownloader alloc] initWithDataDownloadString:@"http://www.freeimageslive.com/galleries/sports/sportsgames/pics/whitedice1.jpg"];
    downloader.delegate = self;
}

-(void) asyncDownloaderDataDownloadComplete:(NSData *)data withError:(bool)error
{
    if (data == nil || error)
    {
        NSLog(@"DOWNLOAD FAILED");
    }
    else
    {
        NSLog(@"DOWNLOAD SUCCEEDED");
    }
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

所以，总结一下，为什么我会遇到问题，该怎么办？

提前致谢 ：）

4

1 回答 1

1

这可能是也可能不是问题，但是当我设置做类似的事情时，我实现了 NSURLConnectionDelegate 和 NSURLConnectionDataDelegate 协议。我没有在 5 之前的 iOS 版本上测试过，但它对我来说在 5 和 6 中都有效：

@interface NIAsyncImageDownloader : NSObject <NSURLConnectionDelegate, NSURLConnectionDataDelegate> {

}
于 2013-06-02T16:37:40.187 回答