簡(jiǎn)述

GCD (Grand Central Dispatch) ,是蘋果開發(fā)的多核編程的解決方案，GCD和其他多線程方案比較起來，使用更簡(jiǎn)單方便。

使用

后臺(tái)執(zhí)行
dispatch_async(dispatch_get_global_queue(0, 0), ^{
        
});

主線程執(zhí)行
dispatch_async(dispatch_get_main_queue(), ^{
        
});

一次性執(zhí)行
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
        
});

延遲執(zhí)行
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        
});

自定義queue
dispatch_queue_t queue = dispatch_queue_create("com.queue.tt", NULL);
dispatch_async(queue, ^{
        
});
dispatch_release(queue);

高級(jí)用法

dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group, dispatch_get_global_queue(0, 0), ^{
        // task 1
 });
dispatch_group_async(group, dispatch_get_global_queue(0, 0), ^{
        // task 2
});
dispatch_group_notify(group, dispatch_get_global_queue(0, 0), ^{
        //任務(wù)執(zhí)行完成
});

后臺(tái)運(yùn)行

@property (assign, nonatomic) UIBackgroundTaskIdentifier ide;

- (void)beginBackTask
{
    self.ide = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
       
        
    }];
}

- (void)endBackTask
{
    [[UIApplication sharedApplication] endBackgroundTask:self.ide];
    self.ide = UIBackgroundTaskInvalid;
}

總結(jié)

總體來說GCD能夠極大地方便開發(fā)者進(jìn)行多線程編程