Smart Mobility

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-selected.png” and “checkbox.png”.

Define the members as follows in “CheckBoxViewController.h”

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

Uncomment the viewDidLoad in “CheckBoxViewController.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.png"];
	[checkBox setBackgroundImage:newNormalImage forState:UIControlStateNormal];
// Image for highlighted state
	UIImage *newHighlightedImage = [UIImage imageNamed:@"checkbox-selected.png"];
	[checkBox setBackgroundImage:newHighlightedImage forState:UIControlStateHighlighted];
// Image for selected state
	UIImage *newSelectedImage = [UIImage imageNamed:@"checkbox-selected.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.