多线程

 1     dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
 2     dispatch_async(queue, ^{
 3         dispatch_group_t group = dispatch_group_create();
 4         dispatch_group_async(group, queue, ^{
 5             
 6         });
 7         dispatch_group_async(group, queue, ^{
 8             
 9         });
10         dispatch_group_notify(group, queue, ^{
11             dispatch_async(dispatch_get_main_queue(), ^{
12                 
13             });
14         });
15     });

 1     //串行队列
 2     dispatch_queue_t serialQueue = dispatch_queue_create("myThreadQueue1", DISPATCH_QUEUE_SERIAL);
 3     //并发队列
 4     dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
 5     for (int i = 0; i < count; ++i) {
 6 //        异步加载
 7         dispatch_async(serialQueue, ^{
 8             [self loadImage:[NSNumber numberWithInt:i]];
 9         });
10 //        同步加载
11         dispatch_sync(serialQueue, ^{
12             [self loadImage:[NSNumber numberWithInt:i]];
13         });
14     }
15     
16     
17     dispatch_barrier_async(globalQueue, ^{
18         [self loadImage:[NSNumber numberWithInt:count - 1]];
19     });
20     for (int i = 0; i < count - 1; ++i) {
21         dispatch_async(globalQueue, ^{
22             [self loadImage:[NSNumber numberWithInt:i]];
23         });
24     }

1     dispatch_queue_t mainQueue = dispatch_get_main_queue();
2     dispatch_sync(mainQueue, ^{
3         [self updateImage:imageData];
4     });
5     
6     dispatch_async(mainQueue, ^{
7         [self updateImage:imageData];
8     });

 1     1、Thread
 2     for (int i = 0; i < ROW_COUNT * COLUMN_COUNT; ++i) {
 3         [NSThread detachNewThreadSelector:@selector(loadImage:) toTarget:self withObject:[NSNumber numberWithInt:i]];
 4         NSThread * thread=[[NSThread alloc] initWithTarget:self selector:@selector(loadImage:) object:[NSNumber numberWithInt:i]];
 5         thread.name=[NSString stringWithFormat:@"myThread%i",i];
 6         [thread start];
 7     }
 8 
 9 
10 
11 
12 
13     [self performSelectorOnMainThread:@selector(updateImage:) withObject:imageData waitUntilDone:YES];
14     [self performSelectorInBackground:@selector(updateImage:) withObject:imageData];

 1     NSOperationQueue * operationQueue = [[NSOperationQueue alloc] init];
 2     operationQueue.maxConcurrentOperationCount = 5;
 3     for (int i = 0; i < count; ++i) {
 4         [operationQueue addOperationWithBlock:^{
 5             [self loadImage:[NSNumber numberWithInt:i]];
 6         }];
 7     }
 8     
 9     依赖关系
10     NSBlockOperation * lastBlockOperation= [NSBlockOperation blockOperationWithBlock:^{
11         [self loadImage:[NSNumber numberWithInt:(count - 1)]];
12     }];
13     for (int i = 0; i < count - 1; ++i) {
14     NSBlockOperation * blockOperation = [NSBlockOperation blockOperationWithBlock:^{
15         [self loadImage:[NSNumber numberWithInt:i]];
16     }];
17         [blockOperation addDependency:lastBlockOperation];
18         [operationQueue addOperation:blockOperation];
19     }
20     
21     [operationQueue addOperation:lastBlockOperation];
22 
23 
24 
25 
26     [[NSOperationQueue mainQueue] addOperationWithBlock:^{
27         [self updateImage:imageData];
28     }];