从UIDatePicker在UIViewControllers之间传递数据

Question

Let me begin to tell you that I am new to Objective C. I have just finished Big Nerd Ranch's book and i want to create a real simple and basic app to learn more. My idea was to create an app that will calculate the weeks between 2 dates. I have created a class for that and tested it. That works.

As you can see below, I have created to views (programmatically), One with the dates and the other will become visible when you click on start or end date.

If you select a date and click on the button 'calculate weeks', you will go back to the first view. No my big question is, how do I get this selected value back to my main screen? I have tried several possibilities and search the web for information, but I couldn't get is to work. I know this should be real easy, but for me at this moment it isn't. :-)

I have created a NSMutableArray that contains the values "Start date" and "End date". My idea was to add the value of the UILabel from the SelectDateView to this array. I have created a property In the inputview @property (readwrite, retain) NSMutableArray *datesArray; for that.

in the selectDateViewController i have created another property @property (nonatomic, assign) BITInputViewController *ivc; so I (in my opinion) can add a value to datesArray.

When I select a date this method is called, it works for the UILabel on SelectDateView, but doesn't do anything with the datesArray.

- (void)LabelChange:(id)sender{

NSDateFormatter *df = [[NSDateFormatter alloc] init];
df.dateStyle = NSDateFormatterMediumStyle;

dateLabel.text = [NSString stringWithFormat:@"%@",
                  [df stringFromDate:datePicker.date]];

[ivc.datesArray addObject:dateLabel.text];

if (ivc.datesArray) {

    for (NSString *d in ivc.datesArray) {
        NSLog(@"This is in datesArray %@",d);
    }
}else NSLog(@"!ivc.datesArray");

}

When I test the app and select a date, I always see "!ivc.datesArray" in the log file.

I also do this check of ivc.datesArray in -(void)viewWillAppear:(BOOL)animated and here I see the current date, as I set this date in - (void)viewDidLoad with this dateLabel.text = [NSString stringWithFormat:@"%@",[df stringFromDate:[NSDate date]]];

(When I print out the array in the inputview, it does show start date and end date, but not the selected date. )

Hopefully someone can give me a few pointers on this.

Answer 1

declare a NSString* date above the @interface in your view1.m file and the create a method in tht first class it should be something like

-(void)passDate:(NSString *)dateString
{

  date = [NSString stringWithFormat:@"%@",dateString];

}

and in your second class create object of first class like
View1 * vc = [[View1 alloc]init];
[vc passDate:df];

Hope it works. You have to declare NSString before the @interface and no property and synthesize.