Show Time in 12 and 24 hour format in UIDatepicker on the basis of app settings not on device Settings

Try this code to show 24 Hrs Format in DatePicker:

NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:@"NL"];
[self.datePicker setLocale:locale];

In Swift

    // myDatePicker is yourUIDatePicker Outlet
    @IBOutlet weak var myDatePicker: UIDatePicker!

    // For 24 Hrs 
    myDatePicker.locale = NSLocale(localeIdentifier: "en_GB") as Locale

    //For 12 Hrs
    timePickerView.locale = NSLocale(localeIdentifier: "en_US") as Locale

For UIDatePicker you cannot change the time format to 24 or 12, it depends on the user local settings in setting.app