dispatch_async 异步执行
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 耗时操作
dispatch_async(dispatch_get_main_queue(), ^{
// 更新界面
});
});
dispatch_once 一次执行
+ (instancetype)defaultInfoCenter {
static InfoCenter *infoCenter = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
infoCenter = [[InfoCenter alloc] init];
});
return infoCenter;
}
dispatch_after 延迟执行
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
NSLog(@"在5s后执行");
});
