在APP开发过程中,经常有需要实现倒计时效果, 比如语音验证码倒计时...代码如下:
__block int timeout = 100;
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_source_t _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
dispatch_source_set_timer(_timer, dispatch_walltime(NULL, 0), 1.0 * NSEC_PER_SEC, 0);
dispatch_source_set_event_handler(_timer, ^{
if (timeout <= 0) {
dispatch_source_cancel(_timer);
}else {
NSLog(@"---%d",timeout);
dispatch_async(dispatch_get_main_queue(), ^{
});
timeout --;
}
});
dispatch_resume(_timer);