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SherginScrollableNavigationBar.swift
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SherginScrollableNavigationBar.swift
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//
// SherginScrollableNavigationBar.swift
// ScrollableNavigationBarDemo
//
// Created by Valentin Shergin on 19/09/14.
// Copyright (c) 2014 shergin research. All rights reserved.
//
import UIKit
enum ScrollState {
case None
case Gesture
case Finishing
}
let ScrollViewContentOffsetPropertyName: String = "contentOffset"
let NavigationBarAnimationName: String = "NavigationBarScrollAnimation"
let DefaultScrollTolerance: CGFloat = 44.0;
public class SherginScrollableNavigationBar: UINavigationBar, UIGestureRecognizerDelegate
{
var scrollView: UIScrollView?
var panGestureRecognizer: UIPanGestureRecognizer!
var scrollTolerance = DefaultScrollTolerance
var scrollOffsetStart: CGFloat = 0.0
var scrollState: ScrollState = .None
var barOffsetStart: CGFloat = 0.0
override init(frame: CGRect) {
super.init(frame: frame)
self.commonInit()
}
required public init(coder: NSCoder) {
super.init(coder: coder)
self.commonInit()
}
func commonInit() {
self.panGestureRecognizer = UIPanGestureRecognizer(target: self, action: "handlePanGesture:")
self.panGestureRecognizer.delegate = self
NSNotificationCenter.defaultCenter().addObserver(
self,
selector: "applicationDidBecomeActive",
name: UIApplicationDidBecomeActiveNotification,
object: nil
)
NSNotificationCenter.defaultCenter().addObserver(
self,
selector: "statusBarOrientationDidChange",
name: UIApplicationDidChangeStatusBarOrientationNotification,
object: nil
)
}
deinit {
NSNotificationCenter.defaultCenter().removeObserver(
self,
name: UIApplicationDidBecomeActiveNotification,
object: nil
)
NSNotificationCenter.defaultCenter().removeObserver(
self,
name: UIApplicationDidChangeStatusBarOrientationNotification,
object: nil
)
self.scrollView = nil
}
func statusBarOrientationDidChange() {
self.resetToDefaultPosition(false);
}
func applicationDidBecomeActive() {
self.resetToDefaultPosition(false);
}
//pragma mark - UIGestureRecognizerDelegate
public func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWithGestureRecognizer otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true;
}
var scrollable: Bool {
let scrollView = self.scrollView!
let contentSize = scrollView.contentSize;
let contentInset = scrollView.contentInset;
let containerSize = scrollView.bounds.size;
let containerHeight = containerSize.height - contentInset.top - contentInset.bottom;
let contentHeight = contentSize.height;
let barHeight = self.frame.size.height;
return contentHeight - self.scrollTolerance - barHeight > containerHeight;
}
var scrollOffset: CGFloat {
let scrollView = self.scrollView!
return -(scrollView.contentOffset.y + scrollView.contentInset.top);
}
var scrollOffsetRelative: CGFloat {
return self.scrollOffset - self.scrollOffsetStart;
}
public func setScrollView(scrollView: UIScrollView?) {
if self.scrollView != nil {
self.scrollView!.removeObserver(
self,
forKeyPath: ScrollViewContentOffsetPropertyName
)
scrollView?.removeGestureRecognizer(self.panGestureRecognizer)
}
self.scrollView = scrollView
if self.scrollView != nil {
scrollView?.addObserver(
self,
forKeyPath: ScrollViewContentOffsetPropertyName,
options: NSKeyValueObservingOptions.New,
context: nil
)
scrollView?.addGestureRecognizer(self.panGestureRecognizer)
}
}
public func resetToDefaultPosition(animated: Bool) {
self.setBarOffset(0.0, animated: animated)
}
override public func observeValueForKeyPath(keyPath: String!, ofObject object: AnyObject!, change: [NSObject : AnyObject]!, context: UnsafeMutablePointer<()>) {
if (self.scrollView != nil) && (keyPath == ScrollViewContentOffsetPropertyName) && (object as NSObject == self.scrollView!) {
self.scrollViewDidScroll()
}
//super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
}
func setBarOffset(offset: CGFloat, animated: Bool) {
var offset: CGFloat = offset;
if offset > 0 {
offset = 0;
}
let barHeight: CGFloat = self.frame.size.height
let statusBarHeight: CGFloat = self.statusBarHeight()
offset = max(offset, -barHeight)
let alpha: CGFloat = min(1.0 - abs(offset / barHeight) + CGFloat(FLT_EPSILON), 1.0)
let currentOffset: CGFloat = self.frame.origin.y
let targetOffset: CGFloat = statusBarHeight + offset
if (abs(currentOffset - targetOffset) < CGFloat(FLT_EPSILON)) {
return;
}
if (animated) {
UIView.beginAnimations(NavigationBarAnimationName, context: nil)
}
let subviews: [UIView] = self.subviews as [UIView]
let backgroundView: UIView = subviews[0]
// apply alpha
for view in subviews {
let isBackgroundView: Bool = (view == backgroundView)
let isInvisible: Bool = view.hidden || view.alpha < CGFloat(FLT_EPSILON)
if isBackgroundView || isInvisible {
continue;
}
view.alpha = alpha;
}
// apply offset
var frame: CGRect = self.frame;
frame.origin.y = targetOffset;
self.frame = frame;
if (animated) {
UIView.commitAnimations()
}
}
var barOffset: CGFloat {
get {
return self.frame.origin.y - self.statusBarHeight()
}
set(offset) {
self.setBarOffset(offset, animated: false);
}
}
func statusBarHeight() -> CGFloat {
let orientation = UIApplication.sharedApplication().statusBarOrientation
let frame = UIApplication.sharedApplication().statusBarFrame
switch (orientation) {
case .Portrait, .PortraitUpsideDown:
return CGRectGetHeight(frame)
case .LandscapeLeft, .LandscapeRight:
return CGRectGetWidth(frame)
default:
assertionFailure("Unknown orientation.")
}
}
func handlePanGesture(gesture: UIPanGestureRecognizer) {
if self.scrollView == nil || gesture.view != self.scrollView {
return
}
let gestureState: UIGestureRecognizerState = gesture.state
if gestureState == .Began {
// Begin state
self.scrollState = .Gesture
self.scrollOffsetStart = self.scrollOffset
self.barOffsetStart = self.barOffset;
}
else if gestureState == .Changed {
// Changed state
self.scrollViewDidScroll()
}
else if
gestureState == .Ended ||
gestureState == .Cancelled ||
gestureState == .Failed
{
// End state
self.scrollState = .Finishing
self.scrollFinishing()
}
}
func scrollViewDidScroll() {
if (!self.scrollable) {
self.resetToDefaultPosition(false);
return;
}
var offset = self.scrollOffsetRelative
var tolerance = self.scrollTolerance
if self.scrollOffsetRelative > 0 {
let maxTolerance = self.barOffsetStart - self.scrollOffsetStart
if tolerance > maxTolerance {
tolerance = maxTolerance;
}
}
if abs(offset) < tolerance {
offset = 0.0;
}
else {
offset = offset + (offset < 0 ? +tolerance : -tolerance);
}
self.barOffset = self.barOffsetStart + offset
self.scrollFinishing();
}
var timer: NSTimer?
func scrollFinishing() {
if let timer = self.timer {
timer.invalidate()
}
if self.scrollState != .Finishing {
return;
}
self.timer = NSTimer.scheduledTimerWithTimeInterval(0.3, target: self, selector: "scrollFinishActually", userInfo: nil, repeats: false)
}
func scrollFinishActually() {
self.scrollState = .None;
var barOffset = self.barOffset;
var barHeight = self.frame.size.height;
if
(abs(barOffset) < barHeight / 2.0) ||
(-self.scrollOffset < barHeight)
{
// show bar
barOffset = 0;
}
else {
// hide bar
barOffset = -barHeight;
}
self.setBarOffset(barOffset, animated:true);
self.barOffsetStart = 0.0;
}
}