Question

I have a UITabBar application, which has three tabs. The first tab has a UIViewController with a UIButton which displays a modal UIViewController to allow the user to select a date. I’m having trouble updating the label of the UIButton when the user has selected their chosen date.

My Main View Controller .h / .m

#import <UIKit/UIKit.h>

@interface SearchViewController : UIViewController {
    IBOutlet UIButton *butFromDate;
}

@property (nonatomic, retain) UIButton *butFromDate;

- (IBAction)pickDate:(id)sender;

@end

////////////////////////////////////////////

#import "SearchViewController.h"
#import "SearchDatePickerViewController.h"

@implementation SearchViewController

@synthesize butFromDate;

- (IBAction)pickDate:(id)sender{
    SearchDatePickerViewController *sampleView = [[[SearchDatePickerViewController alloc] init] autorelease];

    [sampleView setModalTransitionStyle:UIModalTransitionStylePartialCurl];
    [self presentModalViewController:sampleView animated:YES];
}

- (void)dealloc {
    [butFromDate release];
    [super dealloc];
}

@end

Then my modal window (with a UIPicker, and a couple of UIBarButtons to cancel or save the user’s choice) .h / .m looks like:

#import <UIKit/UIKit.h>

@interface SearchDatePickerViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource> {
    NSMutableArray *dates;
    IBOutlet UIPickerView *picker;
}

@property (nonatomic, retain) NSMutableArray *dates;
@property (nonatomic, retain) UIPickerView *picker;

- (IBAction)cancelDatePick:(id)sender;
- (IBAction)pickDate:(id)sender;

@end

////////////////////////////////////////////

#import "SearchDatePickerViewController.h"
#import "SearchViewController.h"
#import "AppDelegate.h"
#import "Search.h"

@implementation SearchDatePickerViewController

@synthesize dates, picker;

- (IBAction)cancelDatePick:(id)sender{
    [self dismissModalViewControllerAnimated:YES];
}

- (IBAction)pickDate:(id)sender{
    HolidayCottagesAppDelegate *appDelegate = (HolidayCottagesAppDelegate *)[[UIApplication sharedApplication] delegate];
    SearchViewController *searchView = [SearchViewController alloc];
    appDelegate.currentSearch.fromDate = [dates objectAtIndex:[picker selectedRowInComponent:0]];

    [searchView.butFromDate setTitle:@"HELLO-TEST" forState:UIControlStateNormal];
    [self dismissModalViewControllerAnimated:YES];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    NSDate* curDate = [NSDate date];
    NSCalendar* calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents* comps = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:curDate];
    NSTimeZone* gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
    dates = [[NSMutableArray alloc] init];

    [comps setTimeZone:gmt];
    [comps setWeekday:7];

    int startCount = comps.week + 1;
    int endCount = (((52 - startCount) + 52) + startCount);

    for (startCount; startCount <= endCount; startCount++){
        NSDate *tDate = [calendar dateFromComponents:comps];
        [dates addObject:tDate];
        [comps setWeek:startCount];
    }
}

// OTHER SHIZZLE HERE BUT NOT REALLY NEEDED TO DISPLAY...

So, when I click the Save button, it runs -(void)pickDate: all ok and dismisses the modal view, but it won’t update the SearchViewController’s UIButton label to “HELLO-TEST”. I’m sure I’m missing something simple here…

Please help me!!

Thanks 🙂

Answer 1

In your main view controller, you need to pass a “self” reference to the search date picker view controller, and then set up an ivar for the main view controller in the search date picker view and use that reference in the pickDate method of the search date picker view. Please check out a blog entry of mine from last year on this exact subject:

http://www.dosomethinghere.com/2009/10/04/passing-values-and-messages-between-views-on-iphone/