获取系统日期和时间戳

Question

我创建了一个方法来将字符串数据写入文本文件。我想知道如何获取系统的日期和时间并将其发送到文本文件中？下面是这个方法：

 -(void) writeToTextFile{

//get the documents dir
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

//file name to write the data to using the documents directory:
NSString *fileName = [NSString stringWithFormat:@"%@/movbandlog.txt",
                      documentsDirectory];
//create content 
NSString *content = @"Data received from device\n \n \n \n \nData sent to Portal\n \n \n \n \nData received to Portal";

//save to documents directory
[content writeToFile:fileName
          atomically:NO
            encoding:NSStringEncodingConversionAllowLossy
               error:nil];

}

- TWcode

Answer 1

纯可可

使用NSDate，并可选择使用NSDateFormatter进行格式化：

NSDate *currentDate = [NSDate date];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd.MM.YY HH:mm:ss"];
NSString *dateString = [dateFormatter stringFromDate:currentDate];
// NSLog(@"%@",dateString);

// Adding your dateString to your content string
NSString *content = [NSString stringWithFormat:@"Data received from device\n \n \n \n \nData sent to Portal\n \n \n \n \nData received to Portal\n \n \n \n \nData received at %@", dateString];

使用Unix函数

您可能还需要考虑使用Unix函数处理未本地化的日期（时间戳）。

struct tm  sometime;
const char *formatString = "%Y-%m-%d %H:%M:%S %z";
(void) strptime_l("2005-07-01 12:00:00 -0700", formatString, &sometime, NULL);
NSLog(@"NSDate is %@", [NSDate dateWithTimeIntervalSince1970: mktime(&sometime)]);
// Output: NSDate is 2005-07-01 12:00:00 -0700

- Michael Robinson

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当然，通常的警告 - 如果时区很重要，请设置时区；如果您不想受到语言环境特性的影响，请设置语言环境。 - Hot Licks

我该如何将这个添加到我的NSString *content中？我需要在文本文件顶部列出日期和时间。 - TWcode

在您的Unix函数中，我有两个问题：1.strptime_l方法会抛出一个警告，尽管我已经包含了<time.h>，如何解决？2.输出的日期是像您在strptime_l方法中编码的那样吗？如何输出当前时间？谢谢。 - Guo Luchuan