iOS 获取GMT 时间

+ (NSString *)currentGMT {
    
    NSDate *date = [NSDate date];
    
    NSTimeZone *tzGMT = [NSTimeZone timeZoneWithName:@"GMT"];
    
    [NSTimeZone setDefaultTimeZone:tzGMT];
    
    NSDateFormatter *iosDateFormater=[[NSDateFormatter alloc]init];
    
    iosDateFormater.dateFormat=@"EEE, dd MMM yyyy HH:mm:ss 'GMT'";
    
    iosDateFormater.locale=[[NSLocale alloc]initWithLocaleIdentifier:@"en_US"];
    
    return [iosDateFormater stringFromDate:date];
}