NSURL委托didReceiveData方法未调用

Question

我知道这已经在很多其他帖子中讨论了但是我需要发布它，因为那些线程不幸地帮助了我。我正在尝试连接到一个rails服务器，它返回一些JSON格式的数据以响应GET请求。我已经实现了NSConnectionDataDelegate的四种方法，如下所示

#pragma mark -
#pragma mark NSURLConnectionDataDelegate

-(void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {

    NSLog(@"didReceiveResponse");
    [resultData setLength:0];

}


-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

    NSLog(@"didReceiveData");
[resultData appendData:data];


}

-(void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {

    NSLog(@"didFailWithError");

    NSString *errDesc = [NSString stringWithFormat:@"Connection failed: %@", [error description]];
    NSLog(@"%@",errDesc);

}

-(void) connectionDidFinishLoading:(NSURLConnection *)connection {

    NSLog(@"didReceiveLoading");
}

在connectionDidFinishDownloading方法（未列出）中，我执行JSON解析但由于 resultData 为空，因为从未调用过didReceiveData方法而失败。

调用didReceiveResponse方法是因为我看到正在记录的消息。服务器在localhost上运行，因此我可以确认收到请求并使用Charles我知道响应是以JSON格式正确接收的。所以在服务器端似乎没有问题。但是从不调用didReceiveData方法。两者都不是didFailWithError方法。

有人可以帮我这个吗？我无法弄清楚我做错了什么。这是我第一次使用NSURL，所以非常感谢。我正在使用ARC在iOS 5上工作。

萨特雅姆

修改

NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"%@%@?%@", kDevelopmentMode ? kLocalHost : kHost, endpoint, parameters]];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
NSURLConnection *urlConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self];

Answer 1

我的猜测是你的应用程序没有收回数据。尝试使用您的网址，它会让您知道返回的原始数据，以及返回数据时的jsonserialization。

NSData *returnedData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://yourURLHere"]];

if (returnedData) {
    NSLog(@"returnedData:%@", returnedData);

    NSDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:returnedData options:kNilOptions error:Nil];
    NSLog(@"jsonDict:%@", jsonDict);
}
else
    NSLog(@"Got Nothing");

如果您的日志显示原始数据和json数据，则问题出在您的NSURLRequest上。但如果日志显示“无所无”，那么您尝试获取的内容就会出现问题。

修改

#import <UIKit/UIKit.h>

@interface AsyncImage : UIImageView 
{    
    NSMutableData *activeDownload;
    NSURLConnection *imageConnection;
}
@property (nonatomic, retain) NSMutableData *activeDownload;
@property (nonatomic, retain) NSURLConnection *imageConnection;
- (void)loadImageFromURL:(NSURL*)url;
@end



#import "AsyncImage.h"

@implementation AsyncImage
@synthesize activeDownload;
@synthesize imageConnection;

- (void)dealloc
{
    [super dealloc];
    NSLog(@"dealloc AsyncImage");

    [activeDownload release];
    [imageConnection cancel];
    [imageConnection release];
}

- (void)cancelDownload
{
    [self.imageConnection cancel];
    self.imageConnection = nil;
    self.activeDownload = nil;
}


#pragma mark -
#pragma mark Download support (NSURLConnectionDelegate)

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [self.activeDownload appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    // Clear the activeDownload property to allow later attempts
    self.activeDownload = nil;

    // Release the connection now that it's finished
    self.imageConnection = nil;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    self.image = [UIImage imageWithData:self.activeDownload];

    self.activeDownload = nil;

    // Release the connection now that it's finished
    self.imageConnection = nil;
}

- (void)loadImageFromURL:(NSURL*)url {
    if (self.imageConnection!=nil) { [imageConnection release]; } //in case we are downloading a 2nd image

    self.activeDownload = [NSMutableData data];
    // alloc+init and start an NSURLConnection; release on completion/failure
    NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:
                             [NSURLRequest requestWithURL:url] delegate:self];
    self.imageConnection = conn;
    [conn release];
}

@end

Answer 2

在.h文件中设置NSURLConnectionDelegate。