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); //每秒执行
dispatch_source_set_event_handler(timer, ^{
//@"倒计时结束，关闭"
dispatch_source_cancel(timer);
dispatch_async(dispatch_get_main_queue(), ^{
if (second >= 0) {
[_getNumBtn setTitle:[NSString stringWithFormat:@"(%ld)重发验证码",second] forState:UIControlStateNormal]; second—;
} else {
//这句话必须写否则会出问题 dispatch_source_cancel(timer); [_getNumBtn setTitle:@"获取验证码" forState:UIControlStateNormal];
}
});
});
dispatch_resume(timer);
