// 睡眠5秒钟,会进入Blocked(阻塞)状态
// [NSThread sleepForTimeInterval:5];
// 3秒后的时间
NSDate *date = [NSDate dateWithTimeIntervalSinceNow:3];
[NSThread sleepUntilDate:date];
// 睡眠5秒钟,会进入Blocked(阻塞)状态
// [NSThread sleepForTimeInterval:5];
// 3秒后的时间
NSDate *date = [NSDate dateWithTimeIntervalSinceNow:3];
[NSThread sleepUntilDate:date];