计时器(验证码倒计时)

来源：互联网发布：仿真软件有哪些编辑：程序博客网时间：2024/06/08 04:03

__block int timeout = 60;    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) {            //倒计时结束，关闭            dispatch_source_cancel(_timer);            dispatch_async(dispatch_get_main_queue(), ^{                //设置界面的按钮显示 根据需要自己设置            });        } else {            dispatch_async(dispatch_get_main_queue(), ^{                //设置界面的按钮显示 根据需要自己设置                NSString *downStr = [NSString stringWithFormat:@"%d%@",timeout, @"s后再次获取"];                timeout--;            });        }    });    dispatch_resume(_timer);

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