iPhone SDK – How To Add CheckBox Control

Thursday

 iPhone SDK – Add CheckBox Control:

                                                                 This is quite a common requirement to be able to add a custom checkbox control in an iPhone app. In the Interface builder -> Tools ->library there is no CheckBox control while other controls like Label and Text Field are there. Here is how I implemented it. I would be interested in hearing about how others went about doing it.

You can use the UIButton control to make a CheckBox.

In your project, in the resources folder add the images e.g. the ones attached with in this post “checkbox_ticked.png” and “checkbox_not_ticked.png”.

 You can right click on, and save as the below images.

Define the members as follows in “ChkBoxViewController.h”

@interface CheckBoxViewController : UIViewController
{
 BOOL checkboxSelected;
 UIButton *checkBox;
 UILabel *checkBoxLabel;
}

Uncomment the viewDidLoad in “ChkBoxViewController.m” and use the following code.

- (void)viewDidLoad
{
    [super viewDidLoad];
    checkBox = [[UIButton alloc] initWithFrame:CGRectMake(60, 100, 16, 16)];
    checkBox.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
    checkBox.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
// Image for normal state
    UIImage *newNormalImage = [UIImage imageNamed:@"checkbox_not_ticked.png"];
    [checkBox setBackgroundImage:newNormalImage forState:UIControlStateNormal];
// Image for highlighted state
    UIImage *newHighlightedImage = [UIImage imageNamed:@"checkbox_ticked.png"];
    [checkBox setBackgroundImage:newHighlightedImage forState:UIControlStateHighlighted];
// Image for selected state
    UIImage *newSelectedImage = [UIImage imageNamed:@"checkbox_ticked.png"];
    [checkBox setBackgroundImage:newSelectedImage forState:UIControlStateSelected];
    [checkBox addTarget:self action:@selector(checkBoxSelect:)forControlEvents:UIControlEventTouchUpInside];
    checkBox.adjustsImageWhenHighlighted = YES;
    [checkBox setBackgroundColor:[UIColor clearColor]];
    [[self view] addSubview:checkBox];
    checkBoxLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, 90, 200, 40)];
    [checkBoxLabel setText:@"Check Box"];
    [checkBox setBackgroundColor:[[ self view] backgroundColor]];
    [[self view] addSubview:checkBoxLabel];
}

And add the following action method

-(void)checkBoxSelect:(id)sender
{
    if (checkboxSelected == 0)
    {
        [checkBox setSelected:YES];
        [checkBoxLabel setText:@"Check Box - Selected"];
        checkboxSelected = 1;
    }
    else
    {
        [checkBox setSelected:NO];
        [checkBoxLabel setText:@"Check Box"];
        checkboxSelected = 0;
    }
}

Build and Run the application, this will work as checkbox control.