NSData为空问题

Question

NSString *urlString = [NSString stringWithFormat:@"%@", item.image];
NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSData * data = [NSData dataWithContentsOfURL:url];

NSDictionary *regsiter=[NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

NSLog(@"response : %@",[regsiter valueForKeyPath:@"response"]);

This NSData values is getting null. And i need to upload image also same this link how its possible please help me....

Answer 1

If data is null, then it means it could not be created. But if you want to know the reason, you should use dataWithContentsOfURL:options:error: method.

Example:

NSError* error = nil;
NSData * data = [NSData dataWithContentsOfURL:url options:nil error:&error];
if (error) {
    NSLog(@"%@", [error localizedDescription]);
}

Answer 2

You can fetch data from URL asynchronously

NSString *url = [NSString stringWithFormat:item.image];
NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:url]];

[NSURLConnection sendAsynchronousRequest:req
                                   queue:[NSOperationQueue mainQueue]
                       completionHandler:^(NSURLResponse *responce,
                                           NSData *data,
                                           NSError *error) {

                           NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
                           NSLog(@"String from URL %@ is %@", url, str);

                       }];