iOS MacOS 系统时间（时间戳）格式化

#pragma mark -原始数据是20220608155116，加工成2022/06/08 15:51:16
-(NSString *)timeString:(NSString *)toIndexstring{
    NSMutableArray *arr = [NSMutableArray array];
      for (int i=0; i<toIndexstring.length; i+=2) {
         
          NSInteger num = 2;
          if (i == 0){
              num = 4;
          }else if (i<4){
              continue;
          }
                  
          NSRange subRange = NSMakeRange(i, num);
          NSString *newStr = [toIndexstring substringWithRange:subRange];
          [arr addObject:newStr];
      }
      
      NSString *arre0 = [arr objectAtIndex:0];
                  NSString *arre1 = [arr objectAtIndex:1];
                  NSString *arre2 = [arr objectAtIndex:2];
                  NSString *arre3 = [arr objectAtIndex:3];
                  NSString *arre4 = [arr objectAtIndex:4];
                  NSString *arre5 = [arr objectAtIndex:5];
                  NSString *rssiConlba = [NSString stringWithFormat:@"%@/%@/%@ %@:%@:%@",arre0,arre1,arre2,arre3,arre4,arre5];
                  
    return rssiConlba;
}