IOS获取两个时间的毫秒差

NSString *savedTime = [[NSUserDefaults standardUserDefaults] stringForKey:@"time"];  

NSString *time = [NSString stringWithFormat:@"%f", (double)[[NSDate date] timeIntervalSince1970]];  

NSLog(@"\n%@\n%@",time,savedTime);  

NSLog(@"%.f",([time doubleValue] - [savedTime doubleValue]) * 1000);  

[[NSUserDefaults standardUserDefaults] setObject:time forKey:@"time"];  

[[NSUserDefaults standardUserDefaults] synchronize];
 

转自：http://blog.csdn.net/rainlesvio/article/details/38271285
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Swift 版本：

let userDefault =
NSUserDefaults.standardUserDefaults()
        let
time = "\((Double)(NSDate().timeIntervalSince1970))"
        if
let savedTime = userDefault.stringForKey("savedTime") {
            print("Now =
\(time), savedTime =
\(savedTime)");
            print("\((Double(time)!
- Double(savedTime)!) * 1000)")
        }
        userDefault.setObject(time, forKey:"savedTime")
        userDefault.synchronize()