网络加载图片

    NSString *aString = @"http://cc.cocimg.com/bbs/attachment/thumb/Fid_12/12_2_52d705803c8c711.png";
    NSData *imageData = [[NSData alloc]initWithContentsOfURL:[NSURL URLWithString:aString]];
    UIImage *aimage = [UIImage imageWithData:imageData];
    UIImageView *imageview = [[UIImageView alloc]initWithImage:aimage];
    imageview.frame = CGRectMake(0, 0, 320, 480);
    [self.view addSubview:imageview];