Animate headerView of TableView while pulling down UITableView in swift - ios

Question

I am trying to create a growing UITableViewHeader on UITableView. I have a UITableView and a mapView set in the tableHeaderView of UITableView.
tblView.bounces = true
tblView.bouncesZoom = true
tblView.alwaysBounceVertical = true
mapView.frame = CGRectMake(0, 0, self.view.frame.size.width, CGFloat(kMapHeaderHeight))
mapView.mapType = MKMapType.Standard
mapView.zoomEnabled=true
mapView.scrollEnabled = true
mapView.delegate = mapHelper
tblView.tableHeaderView = mapView
And also implemented scrollViewDidScroll delegate and whenever it scrolls down, I have changed the frame of headerview as
func scrollViewDidScroll(scrollView: UIScrollView) {
var scrollOffset = scrollView.contentOffset.y
println("\(scrollOffset)")
var headerFrame : CGRect = self.mapView.frame
if (scrollOffset < 0){
headerFrame.size.height -= scrollView.contentOffset.y/3
}
self.mapView.frame = headerFrame
}
However, it does not grow as expected without bouncing.Seems very unclear. Any help?
I am following these tutorials to create a Growing UITableViewheader when pulling down as
UITableVIew header without bouncing when pull down ,
Expand UITableView Header View to Bounce Area When Pulling Down
Here is the link of the project :
https://drive.google.com/file/d/0B6dTvD1JbkgBVENUS1ROMzI0Wnc/vie
EDITED: i somehow managed to have the effect but the animation seems very slow
func scrollViewDidScroll(scrollView: UIScrollView) {
let yPos: CGFloat = -scrollView.contentOffset.y
if (yPos > 0) {
var mapViewRect: CGRect = self.mapView.frame
mapViewRect.origin.y = scrollView.contentOffset.y
mapViewRect.size.height = kHeaderHeight+yPos
self.mapView.frame = mapViewRect
}
}
let kHeaderHeight:CGFloat = 200

Answer 1

I suggest you to use this tutorial.
The most important parts of it:
Create a scrollView (or whatever that is a subclass of a UIScrollView) and a separate view (which will be functioning as a headerView, so let's call if headerView)
add the headerView and the scrollView as a subView of your view
implement the scrollViewDidScroll method, and put the framing logic there (of course, if you're using autolayout, you have to manage constraints there)

Answer 2

Actually the animation was not working well in simulator of xcode6.3. I tried 2 days for this and posted a bounty here but when i finally I tested it on real device and found the MapView was properly bouncing.If anyone needs it..here is the piece of logic.
let kHeaderHeight:CGFloat = 380
class NewBookingVC: UIViewController {
#IBOutlet weak var tblView: UITableView!
let mapView : MKMapView = MKMapView()
var customTableHeaderView:UIView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
tblView.delegate = self
tblView.dataSource = self
mapView.frame = CGRectMake(0, 0, self.view.frame.size.width, 380)
mapView.mapType = MKMapType.Standard
mapView.zoomEnabled=true
mapView.scrollEnabled = true
customTableHeaderView = UIView(frame: CGRectMake(0, 0, self.view.frame.size.width, 380))
customTableHeaderView.addSubview(mapView)
tblView.tableHeaderView = customTableHeaderView
}
func scrollViewDidScroll(scrollView: UIScrollView) {
let yPos: CGFloat = -scrollView.contentOffset.y
if (yPos > 0) {
var mapViewRect: CGRect = self.mapView.frame
mapViewRect.origin.y = scrollView.contentOffset.y
mapViewRect.size.height = kHeaderHeight+yPos
self.mapView.frame = mapViewRect
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 3

Actually what you have to do is implement the scrollview delegate for table view because it inherits from scrollview and you can implement scrollViewDidScroll delegate and whenever it scrolls down, change the frame of headerview.
Idea behind this while scrolling you always have to keep the y-position of the MKMapView at the zero position....and height should incerase accordingly...
func scrollViewDidScroll(scrollView: UIScrollView) {
let yPos: CGFloat = -scrollView.contentOffset.y
if (yPos > 0) {
//adjust your mapview y-pos and height
//adjusting new position is all about real math
}
}
Performance in the iOS Simulator is not expected to match performance on device. The iOS Simulator is meant as a tool for rapid prototyping and fast iteration.In your case too, redrawing of MapView performance is quite slow in the simulator because at each Scroll you are calculating its new frame and height. So it takes some time adjusting new frame and seems very slow.
However it works well while tuning on real devices.