How to get the time in am/pm format iphone NSDateF

问题:

Am working in an iPhone app with using the NSDateFormatter. Am getting the time from the webservice like "00:00:00", "16:00:00","15:30:00" and so on. I need to convert these time to if the time is "00:00:00" to "12 AM", if the time is "16:00:00" to "4 PM", if the time is "15:30:00" to "3.30 PM". I have used the below code to this but when i have pass "16:00:00" the date returns null.

 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];

When am passing "00:00:00" it is returning "12 AM" correctly. Can anyone please help me to solve this issue? Thanks in advance.

回答1:

If your time format is in 24hrs please use "HH:mm:ss" format. Please test the code and let me know if it is working for you. I have tested and it is returning "4 PM"

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];

Thanks.

回答2:

Why are you again allocating the NSDateFormatter ?

you Just need to format it to NSDate and then again to 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);

回答3:

Try HH:mm:ss (notice the capitals in the hour format)

回答4:

You can use the .ShortStyle which will adapt to the current locale:

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

Which returns 17:12 or 5:12 PM depending on the current device locale.

回答5:

This Below code always keep in 12hour format:

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

This always keep in 24 hour format

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

回答6:

Hope someone would be helpful who would like to get it in Swift

For 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)

回答7:

your date format should be:

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

check the Date Format Pattern Doku