Further support for countdown timer

These changes should fix #72

Added an additional initialiser which allows to set the countdown timer
to an initial countdown interval.

Changed picker view configuration regarding the existence of countdown
timer.

Pickers/ActionSheetDatePicker.h

@@ -54,6 +54,10 @@ typedef void(^ActionDateCancelBlock)(ActionSheetDatePicker *picker);
 
 - (id)initWithTitle:(NSString *)title datePickerMode:(UIDatePickerMode)datePickerMode selectedDate:(NSDate *)selectedDate target:(id)target action:(SEL)action origin:(id)origin cancelAction:(SEL)cancelAction;
 
+// mgm: additional initializer which allows to set countdownduration
+- (id)initWithTitle:(NSString *)title datePickerMode:(UIDatePickerMode)datePickerMode countDownDuration:(NSTimeInterval)duration target:(id)target action:(SEL)action origin:(id)origin cancelAction:(SEL)cancelAction;
+
+
 - (instancetype)initWithTitle:(NSString *)title
                datePickerMode:(UIDatePickerMode)datePickerMode
                  selectedDate:(NSDate *)selectedDate

Pickers/ActionSheetDatePicker.m

@@ -84,6 +84,18 @@ - (id)initWithTitle:(NSString *)title datePickerMode:(UIDatePickerMode)datePicke
     return self;
 }
 
+// mgm: additional initializer which allows to set countdownduration
+- (id)initWithTitle:(NSString *)title datePickerMode:(UIDatePickerMode)datePickerMode countDownDuration:(NSTimeInterval)duration target:(id)target action:(SEL)action origin:(id)origin cancelAction:(SEL)cancelAction
+{
+    self = [super initWithTarget:target successAction:action cancelAction:cancelAction origin:origin];
+    if (self) {
+        self.title = title;
+        self.datePickerMode = datePickerMode;
+        self.duration = duration;
+    }
+    return self;
+}
+
 - (instancetype)initWithTitle:(NSString *)title
                datePickerMode:(UIDatePickerMode)datePickerMode
                  selectedDate:(NSDate *)selectedDate
@@ -110,7 +122,15 @@ - (UIView *)configuredPickerView {
     datePicker.timeZone = self.timeZone;
     datePicker.locale = self.locale;
 
-    [datePicker setDate:self.selectedDate animated:NO];
+    // mgm: Set the datePicker according to mode
+    // if datepicker is set with a date in countdownmode then
+    // 1h is added to the initial countdown
+    if (self.datePickerMode == UIDatePickerModeCountDownTimer) {
+        datePicker.countDownDuration = self.duration;
+    } else {
+        [datePicker setDate:self.selectedDate animated:NO];
+    }
+
     [datePicker addTarget:self action:@selector(eventForDatePicker:) forControlEvents:UIControlEventValueChanged];
 
     //need to keep a reference to the picker so we can clear the DataSource / Delegate when dismissing (not used in this picker, but just in case somebody uses this as a template for another picker)
@@ -131,6 +151,7 @@ - (void)notifyTarget:(id)target didSucceedWithAction:(SEL)action origin:(id)orig
 #pragma clang diagnostic ignored "-Warc-performSelector-leaks"
         if (self.datePickerMode == UIDatePickerModeCountDownTimer) {
             [target performSelector:action withObject:@(self.duration) withObject:origin];
+
         } else {
             [target performSelector:action withObject:self.selectedDate withObject:origin];
         }