Question

im newbie developer and creating my first iphone app… and i have one little problem 🙂

i switching in my program 2 views, secondView is over firstView, and when i press 2 times or more on button to show the SecondView iphone simulator stopping worling and if after i press to show the FirstView he still showing SecondView view :(…

and i need help how to make button to pressing one time only, and if after switch back to FirstView to can again press one time,and shows like presse,now it show pressed only when i tuch it,… i want like buttons in TabBar, and if i use the TabBar is more harder for me i dont know how to resize it to height and add custom background, and change the effect of pushed button

Thanks you very much and sorry for my bad english!.

here is what code i use to switching views with buttons

 //   FirstView.h
 #import <UIKit/UIKit.h>

@interface FirstView : UIViewController {

}

-(IBAction) goToSecondView:(id) sender;
-(IBAction) goToFirstView:(id) sender;

@end

//    FirstView.m
#import "FirstView.h"

#import "SecondView.h"

@implementation FirstView

SecondView *secondView;

-(IBAction) goToSecondView:(id) sender{
   secondView = [[SecondView alloc] initWithNibName:@"SecondView" bundle:nil]; 
   [self.view addSubview:secondView.view];
}

 -(IBAction) goToFirstView:(id) sender {      
    [secondView.view removeFromSuperview];
}

thank you very much!

Answer 1

This:

@implementation FirstView

SecondView *secondView;

… is most likely the source of your crash. You shouldn’t define instance variables in the implementation. The compiler may allow it but the runtime will be confused and the instance variable will not be properly retained.

You should define it like:

@interface FirstView : UIViewController {
    SecondView *secondView;
}
@property(nonatomic, retain) SecondView *secondView;

…and use it like:

-(IBAction) goToSecondView:(id) sender{
   UIView *newView = [[SecondView alloc] initWithNibName:@"SecondView" bundle:nil];
   self.secondView=newView;
   [newView release];
   [self.view addSubview:self.secondView.view];
}

For clarity you should also rename FirstView and SecondView to FirstViewController and SecondViewController because they are view controllers and not views themselves.

More generally, what you are trying to do is dangerous and difficult. You don’t swap views by adding and removing them as subviews. You need to swap out view controller and their views using a UINavigationController or a UITabbarController. In Xcode File>New Project, there is a Navigation based project and a Tabbar based project templates. Either will provide you most of the code you need to implement a simple app using either controller.

It will be well worth your time to spend a day learning how to use these controllers properly. With your current design, your app will break if it gets much more than two views.