iOS 5 Programming Cookbook

2.5. Implementing Range Pickers with UISlider

Problem

You would like to allow your users to specify a value within a range, using an easy-to-use and intuitive UI.

Solution

Use the UISlider class.

Discussion

You’ve certainly seen sliders before. Figure 2-18 shows an example.

Figure 2-18. The volume slider at the bottom of the screen

To create a slider, instantiate an object of type UISlider. Let’s dive right in and create a slider and place it on our view controller’s view. We’ll start with our view controller’s header file:

#import <UIKit/UIKit.h>

@interface Implementing_Range_Pickers_with_UISliderViewController
           : UIViewController

@property (nonatomic, strong) UISlider *mySlider;

@end

And then let’s synthesize the mySlider property:

#import "Implementing_Range_Pickers_with_UISliderViewController.h"

@implementation Implementing_Range_Pickers_with_UISliderViewController

@synthesize mySlider;

...

And now let’s go to the viewDidLoad method and create our slider component. In this code, we are going to give our slider a range between 0 to 100 and set its default position to be halfway between start and end.

Note

The range of a slider has nothing to do with its appearance. We use the range specifiers of a slider to tell the slider to calculate its value based on the relative position within the range. For instance, if the range of a slider is provided as 0 to 100, when the knob on the slider is on the ...