IOS-GCD-下載圖片

#import "ViewController.h"

@interface ViewController ()
@property(nonatomic, strong) UIScrollView *scrollView;
@property(nonatomic, strong) UIImageView *imageView;
@end

@implementation ViewController

- (void)loadView {
    
    self.scrollView =[[UIScrollView alloc] initWithFrame:[UIScreen mainScreen].bounds];
    self.scrollView.backgroundColor = [UIColor whiteColor];
    self.view = self.scrollView;
    self.imageView = [[UIImageView alloc] init];
    [self.scrollView addSubview:self.imageView];
    
    
}


- (void)viewDidLoad {
    [super viewDidLoad];
    
    // Do any additional setup after loading the view, typically from a nib.

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSURL *url = [NSURL URLWithString:@"http://pic9.nipic.com/20100824/2531170_082435310724_2.jpg"];
        NSData *data = [NSData dataWithContentsOfURL:url];
        UIImage *img = [UIImage imageWithData:data];
        
        dispatch_sync(dispatch_get_main_queue(), ^{
        
            self.imageView.image = img;
            [self.imageView sizeToFit];
            self.scrollView.contentSize = img.size;
        });
        
    });
}



- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end

複製代碼