重新格式化字符串

Question

我需要幫助。，我有這個日期在這種格式的UIlabel 04/26/2013。我怎樣才能重新格式化爲04.26.2013？我已經有如下代碼：

UILabel *timelabel = [[UILabel alloc] initWithFrame:CGRectMake(xx, xx, xx, xx)]; 
[timelabel setText:dateToday]; 

dateToday值04/26/2013。

Answer 1

timelabel.text = [dateToday stringByReplacingOccurrencesOfString:@"/" withString:@"."]; 

Answer 2

NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init]; 
[dateFormat setDateFormat:@"MM.dd.yyyy"]; 
NSString *stringFromDate = [formatter stringFromDate:[NSDate date]]; 
NSLog(@"today : %@", stringFromDate); 

Answer 3

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init]; 
[dateFormatter setDateFormat:@"MM.dd.yyyy"]; 
NSDate *date = [dateFormatter dateFromString:dateToday]; 
if(date != nil) { 
    NSString *formattedDateString = [dateFormatter stringFromDate:date]; 
    [timelabel setText:formattedDateString]; 
} else { 
    [timelabel setText:@"Invalid Date"]; 
} 

添加錯誤檢查。總是檢查輸入字符串是否是有效的日期字符串。

參考：Date Formatting Guide (though it is for Mac; iOS applies the same)