Swift UIScrollView snap to subview width without pagingEnabled - ios

Question

How can i implement UIScrollView when swiping snap to its subviews width. I need it to behave like pagingEnabled but i cant enable paging because i need my entire view can be swipe to scroll. if i do pagingEnable its impossible because scrollview bounds will be change to subviews width.
is there any possible way to do this.
please check the image for more details
import UIKit
class ViewController: UIViewController{
var navigationScroller: UIScrollView!
var contentScroller: UIScrollView!
var navContainer: UIView!
var contentContainer: UIView!
var selfWidth:CGFloat?
var navigationLabels = ["EVENTS", "MEMBERS", "SECTORS", "ORGANIZATIONS", "SEARCH", "EVENTS", "MEMBERS"]
private var buttonsTextFontAndSize: UIFont = UIFont(name: "HelveticaNeue-Light", size: 14)!
override func viewDidLoad() {
super.viewDidLoad()
selfWidth = self.view.frame.width
let frameWidth = self.view.frame.width
let frameHeight = self.view.frame.height
//let navscrollPosition = CGFloat( (frameWidth/2) - (75.0/2) )
navContainer = UIView(frame: CGRectMake(0.0, 75.0, frameWidth, 40.0))
navContainer.backgroundColor = UIColor(red:0, green:0.302, blue:0.522, alpha:1)
navigationScroller = UIScrollView(frame: CGRectMake(0.0, 0.0, frameWidth, 40.0))
navigationScroller.backgroundColor = UIColor.clearColor()
navigationScroller.pagingEnabled = false
navigationScroller.showsHorizontalScrollIndicator = false
navigationScroller.showsVerticalScrollIndicator = false
navigationScroller.clipsToBounds = false
navigationScroller.contentInset = UIEdgeInsetsZero
//navigationScroller.userInteractionEnabled = false
//navigationScroller.
addNavigationLabels(navigationScroller)
self.view.addSubview(navContainer)
navContainer.addSubview(navigationScroller)
navigationScroller.contentSize = CGSize(width: 150.0 * CGFloat(navigationLabels.count),height: 40.0)
navigationScroller.contentOffset = CGPoint(x: 170.0, y:0.0)
contentContainer = UIView(frame: CGRectMake(0.0, 115.0, frameWidth, frameHeight-115.0))
contentContainer.backgroundColor = UIColor.clearColor()
contentScroller = UIScrollView(frame: CGRectMake(0.0, 0.0, frameWidth, frameHeight-115.0))
contentScroller.backgroundColor = UIColor.clearColor()
contentScroller.pagingEnabled = true
contentScroller.showsHorizontalScrollIndicator = false
contentScroller.showsVerticalScrollIndicator = false
contentScroller.clipsToBounds = true
contentScroller.contentInset = UIEdgeInsetsZero
//contentScroller.addSubview(navContainer)
addContents(contentScroller)
self.view.addSubview(contentContainer)
contentContainer.addSubview(contentScroller)
contentScroller.contentSize = CGSize(width: frameWidth * CGFloat(navigationLabels.count),
height: frameHeight-115.0)
//contentScroller.delegate = self
navigationScroller.delegate = self
}
//MARK: -View Appeared function
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(true)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
// MARK: -Adding navigation labels fron navigation labels array
private func addNavigationLabels(navScrollView:UIScrollView){
var buttonsXPosition: CGFloat = 0
var buttonNumber = 0
for navLabel in navigationLabels {
var navButton: UIButton!
let red = CGFloat(buttonNumber) - 0.9
let frameWidth = self.view.frame.width
navButton = UIButton(frame: CGRectMake(buttonsXPosition, 0, frameWidth/3, 40.0))
navButton.titleLabel!.font = buttonsTextFontAndSize
navButton.contentHorizontalAlignment = .Center
navButton.backgroundColor = UIColor(red:red , green:0.114, blue:0.286, alpha:1)
navButton.setTitle(navLabel, forState: UIControlState.Normal)
navButton.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)
navScrollView.addSubview(navButton)
buttonsXPosition = frameWidth/3 + buttonsXPosition
buttonNumber++
}
}
func buttonAction(sender:UIButton!){
print("pressed")
}
// MARK: -Adding navigation labels fron navigation labels array
private func addContents(contentScroller:UIScrollView){
var buttonsXPosition: CGFloat = 0
var buttonNumber = 0
let frameWidth = self.view.frame.width
let frameHeight = self.view.frame.height
for navLabel in navigationLabels {
var navButton: UIButton!
navButton = UIButton(frame: CGRectMake(buttonsXPosition, 40.0, frameWidth, frameHeight-155))
navButton.titleLabel!.font = buttonsTextFontAndSize
navButton.contentHorizontalAlignment = .Center
navButton.backgroundColor = UIColor.darkGrayColor()
navButton.setTitle(navLabel, forState: UIControlState.Normal)
contentScroller.addSubview(navButton)
buttonsXPosition = frameWidth + buttonsXPosition
buttonNumber++
}
}
}
app view

Answer 1

You can implement UIScrollViewDelegate's method scrollViewWillEndDragging:withVelocity:targetContentOffset: and modify the offset at it will finish decelerating to match the width that you wish.
Something like this:
class ScrollSample: NSObject, UIScrollViewDelegate {
func scrollViewWillEndDragging(scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
let targetOffset = targetContentOffset.memory.x
// Round the offset to be a multiple of scrollview width
let roundedOffset = round(targetOffset / scrollView.frame.width) * scrollView.frame.width
targetContentOffset.memory = CGPoint(x: roundedOffset, y: 0)
}
}