Question

I’m working on an application in which I’m adding UIBarButtonItem to UIToolbar dynamically. When User clicks on a bar button. I’m changing it’s tint color to red.
But for some bar buttons it’s not working and the application is crashing.

Here is my code:

@interface myClass : UIViewController

@property (nonatomic, retain) NSMutableArray *barButtonItems;
@property (nonatomic, retain) IBOutlet UIToolbar *toolBar;

@end


@implementation myClass 

@sythesize barButtonItems, toolBar;

- (void)viewDidLoad
{
  [super viewDidLoad];
  barButtonItems = [[NSMutableArray alloc] init];
  [self initToolBar];
}

//To set the tool bar 
- (void)initToolBar
{
   [self addBarItem:@"PlantDetails" actionName:@"createPlantDetails:"];
   [self addBarItem:@"ElectricalEquipmentInventory" actionName:@"createInventory:button:"];
   toolBar.items = barButtonItems;
}

//Create bar button item
- (void)addBarItem:(NSString*)barButtonName actionName:(NSString*)methodName
{
   UIBarButtonItem *plantDetails = [[UIBarButtonItem alloc] initWithTitle:barButtonName style:UIBarButtonItemStyleDone target:self action:NSSelectorFromString(methodName)];
   [barButtonItems addObject:plantDetails];
   [plantDetails release];
   plantDetails = nil; 
}


//Changes the barbutton tintcolor when user selected
-(void)changeSelection:(UIBarButtonItem *)button
{
   NSArray *tempArray = toolBar.items;
   for(int loop = 0; loop<[tempArray count]; loop++)
       [[tempArray objectAtIndex:loop] setTintColor:[UIColor blackColor]];
   [button setTintColor:[UIColor redColor]];
}


//First bar button method
- (void)createPlantDetails:(UIBarButtonItem *)button
{
   [self changeSelection:button];
   NSLog(@"createPlantDetails");
}

//second bar button method
- (void)createInventory:(int)selectedIndex button:(UIBarButtonItem *)button
{
   [self changeSelection:button];
   NSLog(@"createInventory");
}

@end

Here my issue is the bar button with only one parameter in it’s selector is working perfectly (createPlantDetails) but when I click on the bar button which have two parameter in it’s selector (createInventory) the application is crashing on [button setTintColor:[UIColor redColor]]; of changeSelection method.

Crash log is something like: touches event have no method like setTintColor .

I searched a lot but couldn’t find a solution. Please help me.

Thanks in advance

Answer 1

The method for the action property has to have one of the following three forms:

- (void)methodName;
- (void)methodName:(id)sender;
- (void)methodName:(id)sender withEvent:(UIEvent *)event;

You can’t use any arbitrary format or custom parameters (the button wouldn’t know what to pass for them).

The createPlantDetails: method works because it matches the second form.

The createInventory:button: method fails because it doesn’t match any of the expected signatures.
Since your method has two parameters, when the button calls the method, the button passes a UIEvent object in the second parameter which in your method is named button.

In changeSelection:, it crashes when it tries to call setTintColor: because button is really a UIEvent and not the UIBarButtonItem (ie. the sender).