如何以iphone NSDateFormatter的am / pm格式获取时间？

Question

我正在使用NSDateFormatter在iPhone应用程序中工作。正在从Web服务中获取时间，例如"00:00:00", "16:00:00","15:30:00" and so on。我需要将这些时间转换为如果时间为"00:00:00" to "12 AM"，则时间为"16:00:00" to "4 PM"，如果时间为“ 15:30:00”至“ 3.30 PM”。我已经将以下代码用于此，但是当我通过"16:00:00" the date returns null时。

 NSString *dats1 = @"16:00:00";
 NSDateFormatter *dateFormatter3 = [[[NSDateFormatter alloc] init] autorelease];
 [dateFormatter3 setDateStyle:NSDateFormatterMediumStyle];  
 [dateFormatter3 setDateFormat:@"hh:mm:ss"]; 
 NSDate *date1 = [dateFormatter3 dateFromString:dats1];
 NSLog(@"date1 : %@", date1); **// Here returning (null)**

 NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
 [formatter setDateFormat:@"hh:mm a"];
 NSLog(@"Current Date: %@", [formatter stringFromDate:date1]); **// Here also returning (null)**
 [formatter release];

传递“ 00:00:00”时，它正确返回“ 12 AM”。谁能帮我解决这个问题？预先感谢。

Answer 1

NSString *dats1 = @"16:00:00";
 NSDateFormatter *dateFormatter3 = [[[NSDateFormatter alloc] init] autorelease];
 [dateFormatter3 setDateStyle:NSDateFormatterMediumStyle];  
 [dateFormatter3 setDateFormat:@"HH:mm:ss"]; 
 NSDate *date1 = [dateFormatter3 dateFromString:dats1];
 NSLog(@"date1 : %@", date1); **// Here returning (null)**

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
 [formatter setDateFormat:@"hh:mm a"];
 NSLog(@"Current Date: %@", [formatter stringFromDate:date1]); **// Here also returning (null)**
 [formatter release];

谢谢。

Answer 2

let timeFormatter = NSDateFormatter()
timeFormatter.dateStyle = .NoStyle
timeFormatter.timeStyle = .ShortStyle
timeFormatter.stringFromDate(NSDate())

哪个返回17:12或5:12 PM，具体取决于当前设备的语言环境。

Answer 3

您只需要将其格式化为NSDate，然后再次格式化为NSString，

    NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
    [dateFormatter setDateFormat:@"HH:mm:ss"];

    NSDate *date = [dateFormatter dateFromString:dats1];

    [dateFormatter setDateFormat:@"hh:mm a"];

    NSString *formattedDate = [dateFormatter stringFromDate:date];

    NSLog(@"%@",formattedDate);

Answer 4

Answer 5

对于Swift

let dateFormatter = NSDateFormatter()
//if some one want 12AM,5PM then use "hh mm a"
//if some one want 00AM,17PM then use "HH mm a"
dateFormatter.dateFormat = "hh mm a"
let stringDate = dateFormatter.stringFromDate(NSDate())
println(stringDate)

Answer 6

NSLocale *12hourFomrat = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"];
df.locale = 12hourFomrat;

此始终保持24小时格式

NSLocale *24hourFormat = [[NSLocale alloc] initWithLocaleIdentifier:@"en_GB"];
df.locale = 24hourFormat

Answer 7

[dateFormatter3 setDateFormat:@"HH:mm:ss"];

检查Date Format Pattern Doku

Answer 8

let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "hh mm a"
let formattedDate = dateFormatter.string(from: Date())