ios - NSURL始终为null

我有一种方法，我在其中调用api并返回这样的字符串

     -(NSString *)urlReturn{

          NSURL *aUrl = [NSURL URLWithString:@"http://deluxecms.net/dev/api/index.php"];
         NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:aUrl
        cachePolicy:NSURLRequestUseProtocolCachePolicy
                                                   timeoutInterval:60.0];
          [request setHTTPMethod:@"POST"];
          NSString *postString =    @"method=getDocument&
         deviceId=cdad86b3d8bca5c09885af94990eda193c40ab03&
      cipher=803ae952ff4a785588397362860d045e&
      version=1&lastSync=0";
        NSLog(@"postString %@",postString);
       [request setHTTPBody:[postString dataUsingEncoding:NSUTF8StringEncoding]];

       NSHTTPURLResponse* urlResponse = nil;
       NSError *error = [[NSError alloc] init];
       NSData *responseData = [NSURLConnection sendSynchronousRequest:request
       returningResponse:&urlResponse error:&error];

    if(error.domain!=nil)
     {
        NSString *errorDesc=[[error userInfo] objectForKey:@"NSLocalizedDescription"];
         NSLog(@"Response Error === %@",errorDesc);
        return nil;
     }

        GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithData:responseData
                                                       options:0 error:&error];
     if (doc == nil) {
        return nil;
     }

      NSArray *partyMembers = [doc nodesForXPath:@"//assets/asset[11]/file" error:nil];
      NSLog(@"ASSTES %@",partyMembers);
        NSString *urlStringmine;
        GDataXMLElement *urlElement = (GDataXMLElement *)[partyMembers objectAtIndex:0];
        urlStringmine = urlElement.stringValue;
        NSLog(@"MY URL STRING %@",urlString);

        return urlStringmine;
    }


    - (void)viewDidLoad
   {
    [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
     urlString = [self urlReturn];
       NSURL *urlPattern = [[NSURL alloc]initWithString:urlString];
       UIImage *image = [UIImage imageWithData: [NSData
      dataWithContentsOfURL:urlPattern]];
     NSLog(@"Imge %@",urlPattern);
     [self.imageView setImage:image];
  }

然后在viewDidLoad方法中，我从该字符串中生成一个url，最后生成一个图像
从这样的URL

但是当我打印urlString时，我得到这样的确切值
http://deluxecms.net/dev/resource/document/Shop/Deluxe screenshot.JPG
但是当我打印urlPattern时，它始终为null。

我无法理解行为？
请帮我。

最佳答案

在使用此命令之前，请尝试转义字符串:

urlString = [[self urlReturn] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];