//將int轉換成NSString
NSString* s = [NSString stringWithFormat:@"%i", i];

//將NSString轉換成int
[nsstring intValue];

//將NSDate轉換成NSString

   NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
   [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSString*strDate = [dateFormatterstringFromDate:_loginResult.dateLastLogin];
    _label.text= strDate;
   [dateFormatter release];

摘自 進階碼農的專欄