Custom UISwitch in iOS

I wanted to create Custom UISwitch in my iOS game. Initially I just waned to change size, font and color and for that I used UICustomSwitch from Hardy Macia found at here. It's quite easy to use and customisable, but then I wanted to switch to use custom image instead of standard one. For that I need to modify code a bit, below is the code which use custom image to create UISwitch. BTW this is how it looks

Header is same as original implementation, but I removed unnecessary properties and added left and right images required to display on and off images for switch.

@interface UICustomSwitch : UISlider {
    BOOL on;
    UIImageView* leftImage;
    UIImageView* rightImage;
 
    BOOL touchedSelf;
}

@property(nonatomic,getter=isOn) BOOL on;
@property (nonatomic, retain) UIImageView* leftImage;
@property (nonatomic, retain) UIImageView* rightImage;

- (void)setOn:(BOOL)on animated:(BOOL)animated;

@end

Now lets see implementation. Below is code for initialising the UISwitch with custom rect. You can also see we are adding On and Off image as left and right subview to switch.

-(id)initWithFrame:(CGRect)rect
{    
    if ((self=[super initWithFrame:rect])) {
 [self awakeFromNib];
    }
    return self;
}

-(void)awakeFromNib
{
    [super awakeFromNib];
 
    self.backgroundColor = [UIColor clearColor];
    
    [self setThumbImage:[Util imageNamed:@"switch"] 
        forState:UIControlStateNormal];
    [self setMinimumTrackTintColor:[UIColor clearColor]];
    [self setMaximumTrackTintColor:[UIColor clearColor]];
    
    self.minimumValue = 0;
    self.maximumValue = 1;
    self.continuous = NO;
 
    self.on = NO;
    self.value = 0.0;
 
    self.leftImage = [[UIImageView alloc] initWithFrame:self.frame];
    self.leftImage.image = [Util imageNamed:@"on"];
    [self addSubview: self.leftImage];
    [self.leftImage release];
    
    self.rightImage = [[UIImageView alloc] initWithFrame:self.frame];
    self.rightImage.image = [Util imageNamed:@"off"];
    [self addSubview: self.rightImage];
    [self.rightImage release];
}

Now you should be able to see UISwitch with custom images, we now need to add code required to on and off switch from code and change image accordingly.

- (void)setOn:(BOOL)turnOn animated:(BOOL)animated;
{
    on = turnOn;
 
    if (animated) {
 [UIView beginAnimations:@"UICustomSwitch" context:nil];
 [UIView setAnimationDuration:0.2];
    }
 
    if (on) {
 self.value = 1.0;
        self.rightImage.hidden = YES;
        self.leftImage.hidden = NO;
    } else {
 self.value = 0.0;
        self.rightImage.hidden = NO;
        self.leftImage.hidden = YES;
    }
 
    if (animated) {
 [UIView commitAnimations]; 
    }
}

Now finally we also have to add code to enable interaction.

- (void)endTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event
{
    [super endTrackingWithTouch:touch withEvent:event];
    touchedSelf = YES;
    [self setOn:on animated:YES];
}

- (void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event
{
    [super touchesBegan:touches withEvent:event];
    touchedSelf = NO;
    on = !on;
}

- (void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event
{
    [super touchesEnded:touches withEvent:event]; 
    if (!touchedSelf) {
 [self setOn:on animated:YES];
 [self sendActionsForControlEvents:UIControlEventValueChanged];
    }
}

That's it, I hope this will help.

Performing Segue and Passing data in iOS

I was trying to learn how to perform view switching using Segue for UI created by StoryBoard. Using Segue is quite easy and convenient. You can create Segue from Interface Builder, which associate action to view. Like if you click some button then you can associate this click action with view switch and you can select which view to switch to. This all is quite simple and can be done using simple drag and drop.

In case you want to perform view switch manually without any user interaction, you can call "performSegueWithIdentifier", like below. Here once my game is finished, I am calling "GameOverSegue", which will switch view to GameOver view.

self.performSegueWithIdentifier("GameOverSegue", sender: self)

If you want to pass some data while performing Segue, your calling ViewController needs to override "prepareForSegue" function. In this function you can set data to called view. Like below, I want to pass score to my GameOver view.

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if( segue.identifier == "GameOverSegue") {
        let gameOverVC: GameOverViewController = 
            segue.destinationViewController as! GameOverViewController;
        gameOverVC.setScore(self.score)
    }
}

Thanks, hope this will be helpful.

Getting UIViewController from UIView

Some time we need reference of view controller from view. While searching for solution I found that view's nextResponder method returns view controller.

In my application I required superview's view controller, Following is code for achieving same.

id superView = [self superview];

id viewController = [superView nextResponder];

[viewController doSomeStuff];

And here is what UIResponder documentation says about nextResponder

UIView implements this method by returning theUIViewController object that manages it (if it has one) or its superview (if it doesn’t); UIViewController implements the method by returning its view’s superview; UIWindow returns the application object, and UIApplication returns nil.