Question

I am having a date format "16-11-2011". but I want to convert it into "16 Nov" I written the code for it but null value generates instead of the format "16 Nov"

我已写了以下法典:

NSDate *checkIn = [[NSUserDefaults standardUserDefaults]valueForKey:@"CHECK_1"];
    NSLog(@"Date: %@",checkIn);

    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];

    [formatter setDateFormat:@"dd MMM"];
    NSString *checkInDate = [formatter stringFromDate:checkIn];
    NSLog(@"checkInDate:%@",checkInDate);

ns statements

Date: 16-11-2011
checkInDate:(null)

因此,我无法将其转化为我想要采用的形式。

plz帮助我解决问题。

Answer 1

I suspect that checkIn is a NSString not NSDate. Therefore, you would have to convert it to a NSDate first and then convert it back to the desired string format.

NSString *checkIn = [[NSUserDefaults standardUserDefaults]valueForKey:@"CHECK_1"];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd-MM-yyyy"];

NSDate *checkInTempDate = [dateFormatter dateFromString:checkIn];

[dateFormatter setDateFormat:@"dd MMM"];
NSString *checkInDate = [dateFormatter stringFromDate:checkInTempDate];

Answer 2

问题是第一点:

NSDate *checkIn = [[NSUserDefaults standardUserDefaults]valueForKey:@"CHECK_1"];

<代码>NSUserDefaults没有一种方法<>ForKey,即“关键价值编码”正在回升。 <0>NSUserDefaults也不适用日期。您从<条码>NSUserDefaults中接过,通过一个附件<代码>NSDate,接受。

最后4行的法典是正确的,但需要日期、检查。这是一种扼杀。

在第一行之后测试这一行的法典,无视任何不兼容的类型警告:

NSLog(@"class name: %s", class_getName([checkIn class]));

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