在GCD中使用顺序队列

@property(nonatomic,retain)dispatch_queue_t serialQueue;

- (void)viewDidLoad {
    [super viewDidLoad];
   
    self.serialQueue=dispatch_queue_create(DISPATCH_QUEUE_SERIAL, 0);
    ...
    

-(void)bigTaskAction{



    dispatch_async(self.serialQueue, ^{
      
        dispatch_sync(dispatch_get_main_queue(), ^{
            
            [self.myActivityIndicator startAnimating];
       
        });
        
        int updateUIWhen=1000;
       
        for (int i=0;i<10000;i++) {
            NSString*newString=[NSString stringWithFormat:@"i=%i",i ];
            NSLog(@"%@ ",newString);
            if (i==updateUIWhen) {
                float f =(float)i/10000;
                NSNumber*percentDone=[NSNumber numberWithFloat:f];

                dispatch_sync(dispatch_get_main_queue(), ^{
                    
                    [self.myProcessView setProgress:[percentDone floatValue ]animated:YES];
                    
                });
                updateUIWhen=updateUIWhen+500;
            }
        }
        dispatch_sync(dispatch_get_main_queue(), ^{
            
            [self.myProcessView setProgress:1.0 animated:YES];

            [self.myActivityIndicator stopAnimating];
        });
    });
    
}

现在只需要button addtarget 剩下的只需要这一个方法就能实现功能