iOS计算系统时间和服务器的时间差

+(NSString *)getTime:(NSString *)timeSource

{

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

[dateFormatter setDateFormat: @"yyyy-MM-dd HH:mm:ss"];

NSDate *date = [dateFormatter dateFromString:timeSource];

NSTimeInterval sec = [date timeIntervalSinceNow];

if (- sec < 86400) {

if (- sec >= 3600) {

int t = - sec / 3600;

return [NSString stringWithFormat:@"%d小时前",t];

}else if (-sec >60) {

int t = - sec / 60 ;

return [NSString stringWithFormat:@"%d分钟前",t];

}else {

return [NSString stringWithFormat:@"%0.f秒前",- sec];

}

}else {

[dateFormatter setDateFormat: @"yyyy年MM月dd日"];

return [dateFormatter stringFromDate:date];

}

}