//每隔一分鐘執(zhí)行一次打印
// GCD定時(shí)器
static dispatch_source_t _timer;
//設(shè)置時(shí)間間隔
NSTimeInterval period = 60.f;
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
_timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);

// 第一次不會(huì)立刻執(zhí)行，會(huì)等到間隔時(shí)間后再執(zhí)行
dispatch_time_t start = dispatch_time(DISPATCH_TIME_NOW, period * NSEC_PER_SEC);
dispatch_source_set_timer(_timer, start, period * NSEC_PER_SEC, 0);

// 第一次會(huì)立刻執(zhí)行，然后再間隔執(zhí)行
dispatch_source_set_timer(_timer, dispatch_walltime(NULL, 0), period * NSEC_PER_SEC, 0);
// 事件回調(diào)
dispatch_source_set_event_handler(_timer, ^{
    dispatch_async(dispatch_get_main_queue(), ^{
        NSLog(@"Count");
        //網(wǎng)絡(luò)請(qǐng)求 doSomeThing...
    });
});
    
// 開(kāi)啟定時(shí)器
if (_timer) {
    dispatch_resume(_timer);
}
    
// 關(guān)閉定時(shí)器
if (_timer) {
    dispatch_source_cancel(_timer);
    _timer = nil;
}

• 第一次不會(huì)立刻執(zhí)行，等到間隔時(shí)間后再循環(huán)執(zhí)行

dispatch_time_t start = dispatch_time(DISPATCH_TIME_NOW, period * NSEC_PER_SEC);
dispatch_source_set_timer(_timer, start, period * NSEC_PER_SEC, 0);

• 第一次會(huì)立刻執(zhí)行，然后再間隔執(zhí)行

dispatch_source_set_timer(_timer, dispatch_walltime(NULL, 0), period * NSEC_PER_SEC, 0);

• 延遲10s執(zhí)行一次

dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW, 10.0 * NSEC_PER_SEC);
dispatch_after(time, dispatch_get_main_queue(), ^{
    NSLog(@"1111111111");
});

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