xcode如何下載圖片！

@implementation ViewController
            
- (void)viewDidLoad {
    [super viewDidLoad];
    
    //這部分是講data數據進行歸檔和解歸檔來下載圖片
    NSString *path = @"http://image.game.uc.cn/2014/8/1/9833190.jpg";
    NSURL *url = [NSURL URLWithString:path];
    NSData *imageData = [NSData dataWithContentsOfURL:url];
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:imageData];
    NSData *data2 = [NSKeyedUnarchiver unarchiveObjectWithData:data];
    [data2 writeToFile:@"/Users/gaozhenyusky/Desktop/image3.jpg" atomically:YES];
    
    //這部分是直接來下載圖片
    NSURL *url2 = [NSURL URLWithString:@"http://image.game.uc.cn/2014/8/1/9833190.jpg"];
    NSData *data3 = [NSData dataWithContentsOfURL:url2];
    [data3 writeToFile:@"/Users/gaozhenyusky/Desktop/image2.jpg" atomically:YES];
}