IOS-NSOperation-下载图片

#import "ViewController.h"

@interface ViewController ()
@property(nonatomic, strong) NSOperationQueue *queue;
@end

@implementation ViewController

- (NSOperationQueue *)queue{
    
    if (_queue == nil) {
        _queue = [[NSOperationQueue alloc] init];
    }
    return _queue;
}

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

    [self.queue addOperationWithBlock:^{
        
        NSLog(@"异步下载图片");
        
        [[NSOperationQueue mainQueue] addOperationWithBlock:^{
            
            NSLog(@"更新UI");
        }];
    }];

}

@end

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