获取系统时间
- (NSString *)currentTime
{
NSDate * senddate=[NSDate date];
NSDateFormatter *dateformatter=[[NSDateFormatter alloc] init];
[dateformatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSString * locationString=[dateformatter stringFromDate:senddate];
NSLog(@"locationString:%@",locationString);
return locationString;
}