GCD定时器

NSTimer 定时器易受 RunLoop模式影响导致定时器不准确。

dispatch_source_t timer;

-(void)runGCDTimer

{

NSLog(@"click run GCD");

__block int count = 0;

dispatch_queue_t queue = dispatch_get_global_queue(0, 0);

timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);

dispatch_time_t start = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3.0 * NSEC_PER_SEC));

uint64_t interval = (uint64_t)(1.0 *NSEC_PER_SEC);

dispatch_source_set_timer(timer, start, interval, 0);

dispatch_source_set_event_handler(timer, ^{

NSLog(@"------------:%@",[NSThread currentThread]);

count ++;

if (count == 5) {

dispatch_source_cancel(timer);

timer = nil;

}

});

dispatch_resume(timer);

}