Changing back button in iOS 7 disables swipe to navigate back

I have an iOS 7 app where I am setting a custom back button like this:

    UIImage *backButtonImage = [UIImage imageNamed:@"back-button"];
UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];


[backButton setImage:backButtonImage forState:UIControlStateNormal];
backButton.frame = CGRectMake(0, 0, 20, 20);


[backButton addTarget:self
action:@selector(popViewController)
forControlEvents:UIControlEventTouchUpInside];


UIBarButtonItem *backBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
viewController.navigationItem.leftBarButtonItem = backBarButtonItem;

But this disables the iOS 7 "swipe left to right" gesture to navigate to the previous controller. Does anyone know how I can set a custom button and still keep this gesture enabled?

EDIT: I tried to set the viewController.navigationItem.backBarButtonItem instead, but this doesn't seem to show my custom image.

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小开

Try self.navigationController.interactivePopGestureRecognizer.enabled = YES;

小开
最佳答案

IMPORTANT: This is a hack. I would recommend taking a look at this answer.

Calling the following line after assigning the leftBarButtonItem worked for me:

self.navigationController.interactivePopGestureRecognizer.delegate = self;

Edit: This does not work if called in init methods. It should be called in viewDidLoad or similar methods.

小开

I also hide the back button, replacing it with a custom leftBarItem.
Removing interactivePopGestureRecognizer delegate after push action worked for me:

[self.navigationController pushViewController:vcToPush animated:YES];


// Enabling iOS 7 screen-edge-pan-gesture for pop action
if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
self.navigationController.interactivePopGestureRecognizer.delegate = nil;
}
小开

I use 

[[UINavigationBar appearance] setBackIndicatorImage:[UIImage imageNamed:@"nav_back.png"]];
[[UINavigationBar appearance] setBackIndicatorTransitionMaskImage:[UIImage imageNamed:@"nav_back.png"]];


[UIBarButtonItem.appearance setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -64) forBarMetrics:UIBarMetricsDefault];
小开

I saw this solution http://keighl.com/post/ios7-interactive-pop-gesture-custom-back-button/ which subclasses UINavigationController. Its a better solution as it handles the case where you swipe before the controller is in place - which causes a crash.

In addition to this I noticed if you do a swipe on the root view controller (after pushing on one, and back again) the UI becomes unresponsive (also same problem in answer above).

So the code in the subclassed UINavigationController should look like so:

@implementation NavigationController


- (void)viewDidLoad {
[super viewDidLoad];
__weak NavigationController *weakSelf = self;


if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
self.interactivePopGestureRecognizer.delegate = weakSelf;
self.delegate = weakSelf;
}
}


- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
// Hijack the push method to disable the gesture
if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
self.interactivePopGestureRecognizer.enabled = NO;
}
[super pushViewController:viewController animated:animated];
}


#pragma mark - UINavigationControllerDelegate


- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animate {
// Enable the gesture again once the new controller is shown
self.interactivePopGestureRecognizer.enabled = ([self respondsToSelector:@selector(interactivePopGestureRecognizer)] && [self.viewControllers count] > 1);
}


@end
小开

Use the backIndicatorImage and backIndicatorTransitionMaskImage properties of the UINavigationBar if at all possible. Setting these on an a UIAppearanceProxy can easily modify behavior across your application. The wrinkle is that you can only set those on ios 7, but that works out because you can only use the pop gesture on ios 7 anyway. Your normal ios 6 styling can remain intact.

UINavigationBar* appearanceNavigationBar = [UINavigationBar appearance];
//the appearanceProxy returns NO, so ask the class directly
if ([[UINavigationBar class] instancesRespondToSelector:@selector(setBackIndicatorImage:)])
{
appearanceNavigationBar.backIndicatorImage = [UIImage imageNamed:@"back"];
appearanceNavigationBar.backIndicatorTransitionMaskImage = [UIImage imageNamed:@"back"];
//sets back button color
appearanceNavigationBar.tintColor = [UIColor whiteColor];
}else{
//do ios 6 customization
}

Trying to manipulate the interactivePopGestureRecognizer's delegate will lead to a lot of issues.

小开 
navigationController.interactivePopGestureRecognizer.delegate = (id<UIGestureRecognizerDelegate>)self;

This is from http://stuartkhall.com/posts/ios-7-development-tips-tricks-hacks, but it causes several bugs:

  1. Push another viewController into the navigationController when swiping in from the left edge of the screen;
  2. Or, swipe in from the left edge of the screen when the topViewController is popping up from the navigationController;

e.g. When the rootViewController of navigationController is showing, swipe in from the left edge of the screen, and tap something(QUICKLY) to push anotherViewController into the navigationController, then

  • The rootViewController does not respond any touch event;
  • The anotherViewController will not be shown;
  • Swipe from the edge of the screen again, the anotherViewController will be shown;
  • Tap the custom back button to pop the anotherViewController, crash!

So you must implement UIGestureRecognizerDelegate method in self.navigationController.interactivePopGestureRecognizer.delegate like this:

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
if (gestureRecognizer == navigationController.interactivePopGestureRecognizer) {
return !navigationController.<#TODO: isPushAnimating#> && [navigationController.viewControllers count] > 1;
}
return YES;
}
小开

I had a similar problem where I was assigning the current view controller as the delegate for the interactive pop gesture, but would break the gesture on any views pushed, or views underneath the view in the nav stack. The way I solved this was to set the delegate in -viewDidAppear, then set it to nil in -viewWillDisappear. That allowed my other views to work correctly.

小开

Imagine we are using Apple's default master/detail project template, where master is a table view controller and tapping on it will show the detail view controller.

We want to customize the back button that appears in the detail view controller. This is how to customize the image, image color, text, text color, and font of the back button.

To change the image, image color, text color, or font globally, place the following in a location that is called before any of your view controllers are created (e.g. application:didFinishLaunchingWithOptions: is a good place).

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
UINavigationBar* navigationBarAppearance = [UINavigationBar appearance];


// change the back button, using default tint color
navigationBarAppearance.backIndicatorImage = [UIImage imageNamed:@"back"];
navigationBarAppearance.backIndicatorTransitionMaskImage = [UIImage imageNamed:@"back"];


// change the back button, using the color inside the original image
navigationBarAppearance.backIndicatorImage = [[UIImage imageNamed:@"back"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
navigationBarAppearance.backIndicatorTransitionMaskImage = [UIImage imageNamed:@"back"];


// change the tint color of everything in a navigation bar
navigationBarAppearance.tintColor = [UIColor greenColor];


// change the font in all toolbar buttons
NSDictionary *barButtonTitleTextAttributes =
@{
NSFontAttributeName: [UIFont fontWithName:@"HelveticaNeue-Light" size:12.0],
NSForegroundColorAttributeName: [UIColor purpleColor]
};


[[UIBarButtonItem appearance] setTitleTextAttributes:barButtonTitleTextAttributes forState:UIControlStateNormal];


return YES;
}

Note, you can use appearanceWhenContainedIn: to have more control over which view controllers are affected by these changes, but keep in mind that you can't pass [DetailViewController class], because it is contained inside a UINavigationController, not your DetailViewController. This means you will need to subclass UINavigationController if you want more control over what is affected.

To customize the text or the font/color of a specific back button item, you must do so in the MasterViewController (not the DetailViewController!). This seems unintuitive because the button appears on the DetailViewController. However once you understand that the way to customize it is by setting a property on a navigationItem, it begins to make more sense.

- (void)viewDidLoad { // MASTER view controller
[super viewDidLoad];


UIBarButtonItem *buttonItem = [[UIBarButtonItem alloc] initWithTitle:@"Testing"
style:UIBarButtonItemStylePlain
target:nil
action:nil];
NSDictionary *barButtonTitleTextAttributes =
@{
NSFontAttributeName: [UIFont fontWithName:@"HelveticaNeue-Light" size:12.0],
NSForegroundColorAttributeName: [UIColor purpleColor]
};
[buttonItem setTitleTextAttributes:barButtonTitleTextAttributes forState:UIControlStateNormal];
self.navigationItem.backBarButtonItem = buttonItem;
}

Note: attempting to set the titleTextAttributes after setting self.navigationItem.backBarButtonItem doesn't seem to work, so they must be set before you assign the value to this property.

小开

I did not write this, but the following blog helped a lot and solved my issues with custom navigation button:

http://keighl.com/post/ios7-interactive-pop-gesture-custom-back-button/

In summary, he implements a custom UINavigationController that uses the pop gesture delegate. Very clean and portable!

Code:

@interface CBNavigationController : UINavigationController <UINavigationControllerDelegate, UIGestureRecognizerDelegate>
@end


@implementation CBNavigationController


- (void)viewDidLoad
{
__weak CBNavigationController *weakSelf = self;


if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
{
self.interactivePopGestureRecognizer.delegate = weakSelf;
self.delegate = weakSelf;
}
}


// Hijack the push method to disable the gesture


- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
self.interactivePopGestureRecognizer.enabled = NO;


[super pushViewController:viewController animated:animated];
}


#pragma mark UINavigationControllerDelegate


- (void)navigationController:(UINavigationController *)navigationController
didShowViewController:(UIViewController *)viewController
animated:(BOOL)animate
{
// Enable the gesture again once the new controller is shown


if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
self.interactivePopGestureRecognizer.enabled = YES;
}

Edit. Added fix for problems when a user tries to swipe left on a root view controller:

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {


if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)] &&
self.topViewController == [self.viewControllers firstObject] &&
gestureRecognizer == self.interactivePopGestureRecognizer) {


return NO;
}


return YES;
}
小开

Create a class 'TTNavigationViewController' which is subclass of 'UINavigationController' and make your existing navigation controller of this class either in storyboard/class, Example code in class - 

    class TTNavigationViewController: UINavigationController, UIGestureRecognizerDelegate {


override func viewDidLoad() {
super.viewDidLoad()
self.setNavigationBarHidden(true, animated: false)


// enable slide-back
if self.responds(to: #selector(getter: UINavigationController.interactivePopGestureRecognizer)) {
self.interactivePopGestureRecognizer?.isEnabled = true
self.interactivePopGestureRecognizer?.delegate  = self
}
}


func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
return true
}}
小开

Here is swift3 version of Nick H247's answer

class NavigationController: UINavigationController {
override func viewDidLoad() {
super.viewDidLoad()
if responds(to: #selector(getter: interactivePopGestureRecognizer)) {
interactivePopGestureRecognizer?.delegate = self
delegate = self
}
}


override func pushViewController(_ viewController: UIViewController, animated: Bool) {
if responds(to: #selector(getter: interactivePopGestureRecognizer)) {
interactivePopGestureRecognizer?.isEnabled = false
}
super.pushViewController(viewController, animated: animated)
}
}


extension NavigationController: UINavigationControllerDelegate {
func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
interactivePopGestureRecognizer?.isEnabled = (responds(to: #selector(getter: interactivePopGestureRecognizer)) && viewControllers.count > 1)
}
}


extension NavigationController: UIGestureRecognizerDelegate {}
小开

RootView

override func viewDidAppear(_ animated: Bool) {
self.navigationController?.interactivePopGestureRecognizer?.isEnabled = false
}

ChildView

override func viewDidLoad() {
self.navigationController?.interactivePopGestureRecognizer?.isEnabled = true
self.navigationController?.interactivePopGestureRecognizer?.delegate = self
}


extension ChildViewController: UIGestureRecognizerDelegate {}
小开

Use this logic to keep enable or disable the swipe gesture..

- (void)navigationController:(UINavigationController *)navigationController
didShowViewController:(UIViewController *)viewController
animated:(BOOL)animate
{
if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)])
{
if (self.navigationController.viewControllers.count > 1)
{
self.navigationController.interactivePopGestureRecognizer.enabled = YES;
}
else
{
self.navigationController.interactivePopGestureRecognizer.enabled = NO;
}
}
}

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