Increment Variable on horizontal UIScrollView slide - swift

Question

How would I increment a variable when the user swipes to the right or left in my horizontal UIScrollView.
For example;
var pageNumber = 1
When the user swipes right it increments by 1 and when swipes left it decrements by 1 -
Here is my scrollView code that is initiated in the viewDidLoad function.
for (var i : Int = 0; i < numberOfQuestions ;i++)
{
//Construct the view by using the Template XIB file
var array : NSArray = NSBundle.mainBundle().loadNibNamed("QuestionView", owner: self, options: nil);
var view : QuestionView = array.objectAtIndex(0) as! QuestionView
// Set the scroll view to global variable
scrollViewQuiz = view
questionLabel.text = questions[currentQuestionIndexView].question
questionViews.addObject(view);
view.setTranslatesAutoresizingMaskIntoConstraints(false);
view.backgroundColor = UIColor.clearColor();
//Add to the scrollView
scrollView.addSubview(view);
//Add the top Constraints, they need to fit the superview
let views : NSDictionary = ["view" : view,"scrollView" : scrollView];
let constraints : NSArray = NSLayoutConstraint.constraintsWithVisualFormat("V:|[view(==scrollView)]|", options: NSLayoutFormatOptions.allZeros, metrics: nil, views: views as [NSObject : AnyObject]);
scrollView.addConstraints(constraints as! [AnyObject]);
// Increments the question
currentQuestionIndexView++
}
contentView.backgroundColor = UIColor.clearColor();
var viewsDictionary : NSMutableDictionary = NSMutableDictionary(dictionary: ["scrollView" : scrollView]);
var visualFormat : NSMutableString = ("H:|").mutableCopy() as! NSMutableString;
//With all the views created, create the Layout Constraints for the horizontal logic
for (var i : Int = 0; i < numberOfQuestions; i++)
{
viewsDictionary.setValue(self.questionViews[i], forKey: NSString(format: "view%d", i) as String);
visualFormat.appendFormat("[view%d(==scrollView)]", i);
}
visualFormat.appendString("|");
constraints = NSLayoutConstraint.constraintsWithVisualFormat(visualFormat as String, options: NSLayoutFormatOptions.allZeros, metrics: nil, views: viewsDictionary as [NSObject : AnyObject]);
scrollView.addConstraints(constraints as! [AnyObject]);
}
View Did Load UPDATE
override func viewDidLoad() {
// QUIZ LOGIC START
shuffleQuestions()
// UI CONSTRAINTS AND VIEW GENERATION
//Example of using 3 questions
var scrollView = self.scrollView;
scrollView.setTranslatesAutoresizingMaskIntoConstraints(false);
self.view.setTranslatesAutoresizingMaskIntoConstraints(false);
self.contentView.setTranslatesAutoresizingMaskIntoConstraints(false);
//Constraints
var constraints : NSArray;
for (var i : Int = 0; i < numberOfQuestions ;i++)
{
//Construct the view by using the Template XIB file
var array : NSArray = NSBundle.mainBundle().loadNibNamed("QuestionView", owner: self, options: nil);
var view : QuestionView = array.objectAtIndex(0) as! QuestionView
// Set the scroll view to global variable
scrollViewQuiz = view
questionLabel.text = questions[currentQuestionIndexView].question
questionViews.addObject(view);
view.setTranslatesAutoresizingMaskIntoConstraints(false);
view.backgroundColor = UIColor.clearColor();
//Add to the scrollView
scrollView.addSubview(view);
//Add the top Constraints, they need to fit the superview
let views : NSDictionary = ["view" : view,"scrollView" : scrollView];
let constraints : NSArray = NSLayoutConstraint.constraintsWithVisualFormat("V:|[view(==scrollView)]|", options: NSLayoutFormatOptions.allZeros, metrics: nil, views: views as [NSObject : AnyObject]);
scrollView.addConstraints(constraints as! [AnyObject]);
let leftSwipeRecognizer = UISwipeGestureRecognizer(target: self, action: "handleLeftSwipe:")
leftSwipeRecognizer.direction = .Left
scrollViewQuiz!.addGestureRecognizer(leftSwipeRecognizer)
let rightSwipeRecognizer = UISwipeGestureRecognizer(target: self, action: "handleRightSwipe:")
rightSwipeRecognizer.direction = .Right
scrollViewQuiz!.addGestureRecognizer(rightSwipeRecognizer)
// Increments the question
currentQuestionIndexView++
}
contentView.backgroundColor = UIColor.clearColor();
var viewsDictionary : NSMutableDictionary = NSMutableDictionary(dictionary: ["scrollView" : scrollView]);
var visualFormat : NSMutableString = ("H:|").mutableCopy() as! NSMutableString;
//With all the views created, create the Layout Constraints for the horizontal logic
for (var i : Int = 0; i < numberOfQuestions; i++)
{
viewsDictionary.setValue(self.questionViews[i], forKey: NSString(format: "view%d", i) as String);
visualFormat.appendFormat("[view%d(==scrollView)]", i);
}
visualFormat.appendString("|");
constraints = NSLayoutConstraint.constraintsWithVisualFormat(visualFormat as String, options: NSLayoutFormatOptions.allZeros, metrics: nil, views: viewsDictionary as [NSObject : AnyObject]);
scrollView.addConstraints(constraints as! [AnyObject]);
}
Update 3 ##
//Add to the scrollView
scrollView.addSubview(view);
scrollView.addSubview(scrollViewQuiz!)
Update 4

Answer 1

I'm assuming you can't use the paging property of UIScrollView.
Contrary to the previous answer, you will actually need two different swipe recognizers. See https://stackoverflow.com/a/7760927/5007059
I understand that you want to detect swipes on the scroll view. To accomplish this, you could add two UISwipeGestureRecognizers to your scrollView, one for left swipes and one for right swipes like so:
// add to viewDidLoad
let leftSwipeRecognizer = UISwipeGestureRecognizer(target: self, action: "handleLeftSwipe:")
leftSwipeRecognizer.direction = .Left
scrollView.addGestureRecognizer(leftSwipeRecognizer)
let rightSwipeRecognizer = UISwipeGestureRecognizer(target: self, action: "handleRightSwipe:")
rightSwipeRecognizer.direction = .Right
scrollView.addGestureRecognizer(rightSwipeRecognizer)
...
// add to your view controller subclass
func handleLeftSwipe(sender: UISwipeGestureRecognizer) {
self.pageNumber = min(PageCount, self.pageNumber + 1)
}
func handleRightSwipe(sender: UISwipeGestureRecognizer) {
self.pageNumber = max(0, self.pageNumber - 1)
}

Answer 2

create swipe gesture
add gesture to the view
var pageNumber = 1
override func viewDidLoad() {
super.viewDidLoad()
///////
let swipeGesture = UISwipeGestureRecognizer(target: self, action: "swipeHandler:")
swipeGesture.direction = .Left | .Right
scrollViewQuiz.addGestureRecognizer(swipeGesture)
}
func swipeHandler( recognizer:UISwipeGestureRecognizer){
switch(recognizer.direction){
case UISwipeGestureRecognizerDirection.Left:
pageNumber--
case UISwipeGestureRecognizerDirection.Right:
pageNumber++
default: break
}
}