Override UIViewController's view property - ios

I want to override my MYViewController : UIViewController's setView: method, such that, I do not allow some one to set view's property to nil.
-(void)setView:(UIView*)view {
if (view == nil)
//ignore - make no change
else
//default performance
}
How can I do this?

Calling the super class only when you want the default behavior should do the work:
-(void)setView:(UIView*)view {
if (view == nil) {
//ignore - make no change
}
else {
//default performance
[super setView:view];
}
}

#synthesize view = _view;
-(void)setView:(UIView*)view {
if (view)
_view = view;
}
It could be done as simple as this. If view is not nil, set the variable.

Related

How to check UIView is empty or not

I have multiple UIView, then after add and remove button on UIView in last want check my view is empty or not.
above image 3rd view is empty how to check programmatically
this view is empty or not.
You can check the amount of subviews in that specific view:
if([theView.subviews count] == 0) {
// View does not contain subviews
}
If you have multiple UIViews inside a parent view and you wish to figure out which views are empty, then loop over the parent subviews and check each if empty or not:
for(UIView * view in parentView.subviews) {
if([view isKindOfClass:[UIView class]] && [view.subviews count] == 0) {
// We found an empty UIView...
// Can you identify this view?
// If you need to do something with it, do it here.
}
}
Try This:
extension UIView {
var isViewEmpty : Bool {
return self.subviews.count == 0 ;
}
}
Paste extension code outside of the viewController class.
After removing button from view, every time check for isViewEmpty as below,
//if you don't have the object of view, you can get view as below,
let view = bottonToRemove.superview;//this will give you obejct for check
//your code to remove button from the view
if view.isViewEmpty {
//implement your logic for if view is empty
}else{
//view not empty
//do you stuff
}
UIView has a property subViews. This will return you an array of all subViews. If the array is null or has count zero then there is no subview in it.
i think as per your requirement you need check there is any button in view or not you can try
BOOL isEmpty = true;
for (UIButton *btn in viewTest.subviews) {
if ([btn isKindOfClass:[UIButton class]]) {
isEmpty = false;
break;
}
}
if (isEmpty == false) {
// there is button in view
}
else
{
// there no button in view
}
Seems like you are checking on the UINavigationBar,
for (UIView *view in self.navigationController.navigationBar.subviews) {
if(view)
//Do your thing
}

Check if a subview is in a view using Swift

How do I test if a subview has already been added to a parent view? If it hasn't been added, I want to add it. Otherwise, I want to remove it.
You can use the UIView method isDescendantOfView:
if mySubview.isDescendant(of: someParentView) {
mySubview.removeFromSuperview()
} else {
someParentView.addSubview(mySubview)
}
You may also need to surround everything with if mySubview != nil depending on your implementation.
This is a much cleaner way to do it:
if myView != nil { // Make sure the view exists
if self.view.subviews.contains(myView) {
self.myView.removeFromSuperview() // Remove it
} else {
// Do Nothing
}
}
}
for view in self.view.subviews {
if let subView = view as? YourNameView {
subView.removeFromSuperview()
break
}
}
Here we used two different views. Parent view is the view in which we are searching for descendant view and check wether added to parent view or not.
if parentView.subviews.contains(descendantView) {
// descendant view added to the parent view.
}else{
// descendant view not added to the parent view.
}

iOS 7 UIWebView keyboard issue

I have to remove this bar as here link but for iOS 7 this code does not work.
We remove this bar with some Objective C runtime trickery.
We have a class which has one method:
#interface _SwizzleHelper : NSObject #end
#implementation _SwizzleHelper
-(id)inputAccessoryView
{
return nil;
}
#end
Once we have a web view which we want to remove the bar from, we iterate its scroll view's subviews and take the UIWebDocumentView class. We then dynamically make the superclass of the class we created above to be the subview's class (UIWebDocumentView - but we cannot say that upfront because this is private API), and replace the subview's class to our class.
#import "objc/runtime.h"
-(void)__removeInputAccessoryView
{
UIView* subview;
for (UIView* view in self.scrollView.subviews) {
if([[view.class description] hasPrefix:#"UIWeb"])
subview = view;
}
if(subview == nil) return;
NSString* name = [NSString stringWithFormat:#"%#_SwizzleHelper", subview.class.superclass];
Class newClass = NSClassFromString(name);
if(newClass == nil)
{
newClass = objc_allocateClassPair(subview.class, [name cStringUsingEncoding:NSASCIIStringEncoding], 0);
if(!newClass) return;
Method method = class_getInstanceMethod([_SwizzleHelper class], #selector(inputAccessoryView));
class_addMethod(newClass, #selector(inputAccessoryView), method_getImplementation(method), method_getTypeEncoding(method));
objc_registerClassPair(newClass);
}
object_setClass(subview, newClass);
}
The equivalent of the above in Swift 3.0:
import UIKit
import ObjectiveC
var swizzledClassMapping = [AnyClass]()
extension UIWebView {
func noInputAccessoryView() -> UIView? {
return nil
}
public func removeInputAccessoryView() {
var subview: AnyObject?
for (_, view) in scrollView.subviews.enumerated() {
if NSStringFromClass(type(of: view)).hasPrefix("UIWeb") {
subview = view
}
}
guard subview != nil else {
return
}
//Guard in case this method is called twice on the same webview.
guard !(swizzledClassMapping as NSArray).contains(type(of: subview!)) else {
return;
}
let className = "\type(of: subview!)_SwizzleHelper"
var newClass : AnyClass? = NSClassFromString(className)
if newClass == nil {
newClass = objc_allocateClassPair(type(of: subview!), className, 0)
guard newClass != nil else {
return;
}
let method = class_getInstanceMethod(type(of: self), #selector(UIWebView.noInputAccessoryView))
class_addMethod(newClass!, #selector(getter: UIResponder.inputAccessoryView), method_getImplementation(method), method_getTypeEncoding(method))
objc_registerClassPair(newClass!)
swizzledClassMapping += [newClass!]
}
object_setClass(subview!, newClass!)
}
}
I've made a cocoapod based on this blog post from #bjhomer.
You can replace the inputaccessoryview and not just hide it. I hope this will help people with the same issue.
https://github.com/lauracpierre/FA_InputAccessoryViewWebView
You can find the cocoapod page right here.
I've came across this awesome solution, but I needed to get the inputAccessoryView back as well. I added this method:
- (void)__addInputAccessoryView {
UIView* subview;
for (UIView* view in self.scrollView.subviews) {
if([[view.class description] hasSuffix:#"SwizzleHelper"])
subview = view;
}
if(subview == nil) return;
Class newClass = subview.superclass;
object_setClass(subview, newClass);
}
It does seem to work as intended with no side effects, but I can't get rid of the feeling that my pants are on fire.
If you want Leo Natan's solution to work with WKWebView instead of UIWebView just change prefix from "UIWeb" to "WKContent".
I created a gist to accomplish this:
https://gist.github.com/kgaidis/5f9a8c7063b687cc3946fad6379c1a66
It's a UIWebView category where all you do is change the customInputAccessoryView property:
#interface UIWebView (CustomInputAccessoryView)
#property (strong, nonatomic) UIView *customInputAccessoryView;
#end
You can either set it to nil to remove it or you can set a new view on it to change it.
Keep in mind, this also uses private API's, so use at your own risk, but it seems like a lot of apps do similar things nonetheless.

How to tell if UIViewController's view is visible

I have a tab bar application, with many views. Is there a way to know if a particular UIViewController is currently visible from within the UIViewController? (looking for a property)
The view's window property is non-nil if a view is currently visible, so check the main view in the view controller:
Invoking the view method causes the view to load (if it is not loaded) which is unnecessary and may be undesirable. It would be better to check first to see if it is already loaded. I've added the call to isViewLoaded to avoid this problem.
if (viewController.isViewLoaded && viewController.view.window) {
// viewController is visible
}
Since iOS9 it has became easier:
if viewController.viewIfLoaded?.window != nil {
// viewController is visible
}
Or if you have a UINavigationController managing the view controllers, you could check its visibleViewController property instead.
Here's #progrmr's solution as a UIViewController category:
// UIViewController+Additions.h
#interface UIViewController (Additions)
- (BOOL)isVisible;
#end
// UIViewController+Additions.m
#import "UIViewController+Additions.h"
#implementation UIViewController (Additions)
- (BOOL)isVisible {
return [self isViewLoaded] && self.view.window;
}
#end
There are a couple of issues with the above solutions. If you are using, for example, a UISplitViewController, the master view will always return true for
if(viewController.isViewLoaded && viewController.view.window) {
//Always true for master view in split view controller
}
Instead, take this simple approach which seems to work well in most, if not all cases:
- (void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
//We are now invisible
self.visible = false;
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
//We are now visible
self.visible = true;
}
For those of you looking for a Swift 2.2 version of the answer:
if self.isViewLoaded() && (self.view.window != nil) {
// viewController is visible
}
and Swift 3:
if self.isViewLoaded && (self.view.window != nil) {
// viewController is visible
}
For over-full-screen or over-context modal presentation, "is visible" could mean it is on top of the view controller stack or just visible but covered by another view controller.
To check if the view controller "is the top view controller" is quite different from "is visible", you should check the view controller's navigation controller's view controller stack.
I wrote a piece of code to solve this problem:
extension UIViewController {
public var isVisible: Bool {
if isViewLoaded {
return view.window != nil
}
return false
}
public var isTopViewController: Bool {
if self.navigationController != nil {
return self.navigationController?.visibleViewController === self
} else if self.tabBarController != nil {
return self.tabBarController?.selectedViewController == self && self.presentedViewController == nil
} else {
return self.presentedViewController == nil && self.isVisible
}
}
}
You want to use the UITabBarController's selectedViewController property. All view controllers attached to a tab bar controller have a tabBarController property set, so you can, from within any of the view controllers' code:
if([[[self tabBarController] selectedViewController] isEqual:self]){
//we're in the active controller
}else{
//we are not
}
I made a swift extension based on #progrmr's answer.
It allows you to easily check if a UIViewController is on screen like so:
if someViewController.isOnScreen {
// Do stuff here
}
The extension:
//
// UIViewControllerExtension.swift
//
import UIKit
extension UIViewController{
var isOnScreen: Bool{
return self.isViewLoaded() && view.window != nil
}
}
For my purposes, in the context of a container view controller, I've found that
- (BOOL)isVisible {
return (self.isViewLoaded && self.view.window && self.parentViewController != nil);
}
works well.
I use this small extension in Swift 5, which keeps it simple and easy to check for any object that is member of UIView.
extension UIView {
var isVisible: Bool {
guard let _ = self.window else {
return false
}
return true
}
}
Then, I just use it as a simple if statement check...
if myView.isVisible {
// do something
}
I hope it helps! :)
Good point that view is appeared if it's already in window hierarchy stack.
thus we can extend our classes for this functionality.
extension UIViewController {
var isViewAppeared: Bool { viewIfLoaded?.isAppeared == true }
}
extension UIView {
var isAppeared: Bool { window != nil }
}
XCode 6.4, for iOS 8.4, ARC enabled
Obviously lots of ways of doing it. The one that has worked for me is the following...
#property(nonatomic, readonly, getter=isKeyWindow) BOOL keyWindow
This can be used in any view controller in the following way,
[self.view.window isKeyWindow]
If you call this property in -(void)viewDidLoad you get 0, then if you call this after -(void)viewDidAppear:(BOOL)animated you get 1.
Hope this helps someone. Thanks! Cheers.
if you're utilizing a UINavigationController and also want to handle modal views, the following is what i use:
#import <objc/runtime.h>
UIViewController* topMostController = self.navigationController.visibleViewController;
if([[NSString stringWithFormat:#"%s", class_getName([topMostController class])] isEqualToString:#"NAME_OF_CONTROLLER_YOURE_CHECKING_IN"]) {
//is topmost visible view controller
}
The approach that I used for a modal presented view controller was to check the class of the presented controller. If the presented view controller was ViewController2 then I would execute some code.
UIViewController *vc = [self presentedViewController];
if ([vc isKindOfClass:[ViewController2 class]]) {
NSLog(#"this is VC2");
}
I found those function in UIViewController.h.
/*
These four methods can be used in a view controller's appearance callbacks to determine if it is being
presented, dismissed, or added or removed as a child view controller. For example, a view controller can
check if it is disappearing because it was dismissed or popped by asking itself in its viewWillDisappear:
method by checking the expression ([self isBeingDismissed] || [self isMovingFromParentViewController]).
*/
- (BOOL)isBeingPresented NS_AVAILABLE_IOS(5_0);
- (BOOL)isBeingDismissed NS_AVAILABLE_IOS(5_0);
- (BOOL)isMovingToParentViewController NS_AVAILABLE_IOS(5_0);
- (BOOL)isMovingFromParentViewController NS_AVAILABLE_IOS(5_0);
Maybe the above functions can detect the ViewController is appeared or not.
If you are using a navigation controller and just want to know if you are in the active and topmost controller, then use:
if navigationController?.topViewController == self {
// Do something
}
This answer is based on #mattdipasquale's comment.
If you have a more complicated scenario, see the other answers above.
you can check it by window property
if(viewController.view.window){
// view visible
}else{
// no visible
}
I needed this to check if the view controller is the current viewed controller, I did it via checking if there's any presented view controller or pushed through the navigator, I'm posting it in case anyone needed such a solution:
if presentedViewController != nil || navigationController?.topViewController != self {
//Viewcontroller isn't viewed
}else{
// Now your viewcontroller is being viewed
}
Window:
window.isVisible
viewController.view.window?.isVisible ?? false
View (macOS):
extension NSViewController {
var isOnScreen: Bool {
return ( self.isViewLoaded && view.window != nil )
}
}

Get to UIViewController from UIView?

Is there a built-in way to get from a UIView to its UIViewController? I know you can get from UIViewController to its UIView via [self view] but I was wondering if there is a reverse reference?
Using the example posted by Brock, I modified it so that it is a category of UIView instead UIViewController and made it recursive so that any subview can (hopefully) find the parent UIViewController.
#interface UIView (FindUIViewController)
- (UIViewController *) firstAvailableUIViewController;
#end
#implementation UIView (FindUIViewController)
- (UIViewController *) firstAvailableUIViewController {
UIResponder *responder = [self nextResponder];
while (responder != nil) {
if ([responder isKindOfClass:[UIViewController class]]) {
return (UIViewController *)responder;
}
responder = [responder nextResponder];
}
return nil;
}
#end
To use this code, add it into an new class file (I named mine "UIKitCategories") and remove the class data... copy the #interface into the header, and the #implementation into the .m file. Then in your project, #import "UIKitCategories.h" and use within the UIView code:
// from a UIView subclass... returns nil if UIViewController not available
UIViewController * myController = [self firstAvailableUIViewController];
UIView is a subclass of UIResponder. UIResponder lays out the method -nextResponder with an implementation that returns nil. UIView overrides this method, as documented in UIResponder (for some reason instead of in UIView) as follows: if the view has a view controller, it is returned by -nextResponder. If there is no view controller, the method will return the superview.
Add this to your project and you're ready to roll.
#interface UIView (APIFix)
- (UIViewController *)viewController;
#end
#implementation UIView (APIFix)
- (UIViewController *)viewController {
if ([self.nextResponder isKindOfClass:UIViewController.class])
return (UIViewController *)self.nextResponder;
else
return nil;
}
#end
Now UIView has a working method for returning the view controller.
Since this has been the accepted answer for a long time, I feel I need to rectify it with a better answer.
Some comments on the need:
Your view should not need to access the view controller directly.
The view should instead be independent of the view controller, and be able to work in different contexts.
Should you need the view to interface in a way with the view controller, the recommended way, and what Apple does across Cocoa is to use the delegate pattern.
An example of how to implement it follows:
#protocol MyViewDelegate < NSObject >
- (void)viewActionHappened;
#end
#interface MyView : UIView
#property (nonatomic, assign) MyViewDelegate delegate;
#end
#interface MyViewController < MyViewDelegate >
#end
The view interfaces with its delegate (as UITableView does, for instance) and it doesn't care if its implemented in the view controller or in any other class that you end up using.
My original answer follows: I don't recommend this, neither the rest of the answers where direct access to the view controller is achieved
There is no built-in way to do it. While you can get around it by adding a IBOutlet on the UIView and connecting these in Interface Builder, this is not recommended. The view should not know about the view controller. Instead, you should do as #Phil M suggests and create a protocol to be used as the delegate.
I would suggest a more lightweight approach for traversing the complete responder chain without having to add a category on UIView:
#implementation MyUIViewSubclass
- (UIViewController *)viewController {
UIResponder *responder = self;
while (![responder isKindOfClass:[UIViewController class]]) {
responder = [responder nextResponder];
if (nil == responder) {
break;
}
}
return (UIViewController *)responder;
}
#end
Combining several already given answers, I'm shipping on it as well with my implementation:
#implementation UIView (AppNameAdditions)
- (UIViewController *)appName_viewController {
/// Finds the view's view controller.
// Take the view controller class object here and avoid sending the same message iteratively unnecessarily.
Class vcc = [UIViewController class];
// Traverse responder chain. Return first found view controller, which will be the view's view controller.
UIResponder *responder = self;
while ((responder = [responder nextResponder]))
if ([responder isKindOfClass: vcc])
return (UIViewController *)responder;
// If the view controller isn't found, return nil.
return nil;
}
#end
The category is part of my ARC-enabled static library that I ship on every application I create. It's been tested several times and I didn't find any problems or leaks.
P.S.: You don't need to use a category like I did if the concerned view is a subclass of yours. In the latter case, just put the method in your subclass and you're good to go.
I modified de answer so I can pass any view, button, label etc. to get it's parent UIViewController. Here is my code.
+(UIViewController *)viewController:(id)view {
UIResponder *responder = view;
while (![responder isKindOfClass:[UIViewController class]]) {
responder = [responder nextResponder];
if (nil == responder) {
break;
}
}
return (UIViewController *)responder;
}
Edit Swift 3 Version
class func viewController(_ view: UIView) -> UIViewController {
var responder: UIResponder? = view
while !(responder is UIViewController) {
responder = responder?.next
if nil == responder {
break
}
}
return (responder as? UIViewController)!
}
Edit 2:- Swift Extention
extension UIView
{
//Get Parent View Controller from any view
func parentViewController() -> UIViewController {
var responder: UIResponder? = self
while !(responder is UIViewController) {
responder = responder?.next
if nil == responder {
break
}
}
return (responder as? UIViewController)!
}
}
Even though this can technically be solved as pgb recommends, IMHO, this is a design flaw. The view should not need to be aware of the controller.
Don't forget that you can get access to the root view controller for the window that the view is a subview of. From there, if you are e.g. using a navigation view controller and want to push a new view onto it:
[[[[self window] rootViewController] navigationController] pushViewController:newController animated:YES];
You will need to set up the rootViewController property of the window properly first, however. Do this when you first create the controller e.g. in your app delegate:
-(void) applicationDidFinishLaunching:(UIApplication *)application {
window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
RootViewController *controller = [[YourRootViewController] alloc] init];
[window setRootViewController: controller];
navigationController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
[controller release];
[window addSubview:[[self navigationController] view]];
[window makeKeyAndVisible];
}
I stumbled upon a situation where I have a small component I want to reuse, and added some code in a reusable view itself(it's really not much more than a button that opens a PopoverController).
While this works fine in the iPad (the UIPopoverController presents itself, therefor needs no reference to a UIViewController), getting the same code to work means suddenly referencing your presentViewController from your UIViewController. Kinda inconsistent right?
Like mentioned before, it's not the best approach to have logic in your UIView. But it felt really useless to wrap the few lines of code needed in a separate controller.
Either way, here's a swift solution, which adds a new property to any UIView:
extension UIView {
var viewController: UIViewController? {
var responder: UIResponder? = self
while responder != nil {
if let responder = responder as? UIViewController {
return responder
}
responder = responder?.nextResponder()
}
return nil
}
}
While these answers are technically correct, including Ushox, I think the approved way is to implement a new protocol or re-use an existing one. A protocol insulates the observer from the observed, sort of like putting a mail slot in between them. In effect, that is what Gabriel does via the pushViewController method invocation; the view "knows" that it is proper protocol to politely ask your navigationController to push a view, since the viewController conforms to the navigationController protocol. While you can create your own protocol, just using Gabriel's example and re-using the UINavigationController protocol is just fine.
I don't think it's "bad" idea to find out who is the view controller for some cases. What could be a bad idea is to save the reference to this controller as it could change just as superviews change.
In my case I have a getter that traverses the responder chain.
//.h
#property (nonatomic, readonly) UIViewController * viewController;
//.m
- (UIViewController *)viewController
{
for (UIResponder * nextResponder = self.nextResponder;
nextResponder;
nextResponder = nextResponder.nextResponder)
{
if ([nextResponder isKindOfClass:[UIViewController class]])
return (UIViewController *)nextResponder;
}
// Not found
NSLog(#"%# doesn't seem to have a viewController". self);
return nil;
}
Swift 4
(more concise than the other answers)
fileprivate extension UIView {
var firstViewController: UIViewController? {
let firstViewController = sequence(first: self, next: { $0.next }).first(where: { $0 is UIViewController })
return firstViewController as? UIViewController
}
}
My use case for which I need to access the view first UIViewController: I have an object that wraps around AVPlayer / AVPlayerViewController and I want to provide a simple show(in view: UIView) method that will embed AVPlayerViewController into view. For that, I need to access view's UIViewController.
Two solutions as of Swift 5.2:
More on the functional side
No need for the return keyword now 🤓
Solution 1:
extension UIView {
var parentViewController: UIViewController? {
sequence(first: self) { $0.next }
.first(where: { $0 is UIViewController })
.flatMap { $0 as? UIViewController }
}
}
Solution 2:
extension UIView {
var parentViewController: UIViewController? {
sequence(first: self) { $0.next }
.compactMap{ $0 as? UIViewController }
.first
}
}
This solution requires iterating through each responder first, so may not be the most performant.
The simplest do while loop for finding the viewController.
-(UIViewController*)viewController
{
UIResponder *nextResponder = self;
do
{
nextResponder = [nextResponder nextResponder];
if ([nextResponder isKindOfClass:[UIViewController class]])
return (UIViewController*)nextResponder;
} while (nextResponder != nil);
return nil;
}
This doesn't answer the question directly, but rather makes an assumption about the intent of the question.
If you have a view and in that view you need to call a method on another object, like say the view controller, you can use the NSNotificationCenter instead.
First create your notification string in a header file
#define SLCopyStringNotification #"ShaoloCopyStringNotification"
In your view call postNotificationName:
- (IBAction) copyString:(id)sender
{
[[NSNotificationCenter defaultCenter] postNotificationName:SLCopyStringNotification object:nil];
}
Then in your view controller you add an observer. I do this in viewDidLoad
- (void)viewDidLoad
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(copyString:)
name:SLCopyStringNotification
object:nil];
}
Now (also in the same view controller) implement your method copyString: as depicted in the #selector above.
- (IBAction) copyString:(id)sender
{
CalculatorResult* result = (CalculatorResult*)[[PercentCalculator sharedInstance].arrayTableDS objectAtIndex:([self.viewTableResults indexPathForSelectedRow].row)];
UIPasteboard *gpBoard = [UIPasteboard generalPasteboard];
[gpBoard setString:result.stringResult];
}
I'm not saying this is the right way to do this, it just seems cleaner than running up the first responder chain. I used this code to implement a UIMenuController on a UITableView and pass the event back up to the UIViewController so I can do something with the data.
It's surely a bad idea and a wrong design, but I'm sure we can all enjoy a Swift solution of the best answer proposed by #Phil_M:
static func firstAvailableUIViewController(fromResponder responder: UIResponder) -> UIViewController? {
func traverseResponderChainForUIViewController(responder: UIResponder) -> UIViewController? {
if let nextResponder = responder.nextResponder() {
if let nextResp = nextResponder as? UIViewController {
return nextResp
} else {
return traverseResponderChainForUIViewController(nextResponder)
}
}
return nil
}
return traverseResponderChainForUIViewController(responder)
}
If your intention is to do simple things, as showing a modal dialog or tracking data, that doesn't justify the use of a protocol. I personally store this function in an utility object, you can use it from anything that implement the UIResponder protocol as:
if let viewController = MyUtilityClass.firstAvailableUIViewController(self) {}
All credit to #Phil_M
Maybe I'm late here. But in this situation I don't like category (pollution). I love this way:
#define UIViewParentController(__view) ({ \
UIResponder *__responder = __view; \
while ([__responder isKindOfClass:[UIView class]]) \
__responder = [__responder nextResponder]; \
(UIViewController *)__responder; \
})
Swiftier solution
extension UIView {
var parentViewController: UIViewController? {
for responder in sequence(first: self, next: { $0.next }) {
if let viewController = responder as? UIViewController {
return viewController
}
}
return nil
}
}
Swift 4 version
extension UIView {
var parentViewController: UIViewController? {
var parentResponder: UIResponder? = self
while parentResponder != nil {
parentResponder = parentResponder!.next
if let viewController = parentResponder as? UIViewController {
return viewController
}
}
return nil
}
Usage example
if let parent = self.view.parentViewController{
}
Updated version for swift 4 : Thanks for #Phil_M and #paul-slm
static func firstAvailableUIViewController(fromResponder responder: UIResponder) -> UIViewController? {
func traverseResponderChainForUIViewController(responder: UIResponder) -> UIViewController? {
if let nextResponder = responder.next {
if let nextResp = nextResponder as? UIViewController {
return nextResp
} else {
return traverseResponderChainForUIViewController(responder: nextResponder)
}
}
return nil
}
return traverseResponderChainForUIViewController(responder: responder)
}
To Phil's answer:
In line: id nextResponder = [self nextResponder]; if self(UIView) is not a subview of ViewController's view, if you know hierarchy of self(UIView) you can use also: id nextResponder = [[self superview] nextResponder];...
If you aren't going to upload this to the App Store, you can also use a private method of UIView.
#interface UIView(Private)
- (UIViewController *)_viewControllerForAncestor;
#end
// Later in the code
UIViewController *vc = [myView _viewControllerForAncestor];
var parentViewController: UIViewController? {
let s = sequence(first: self) { $0.next }
return s.compactMap { $0 as? UIViewController }.first
}
My solution would probably be considered kind of bogus but I had a similar situation as mayoneez (I wanted to switch views in response to a gesture in an EAGLView), and I got the EAGL's view controller this way:
EAGLViewController *vc = ((EAGLAppDelegate*)[[UIApplication sharedApplication] delegate]).viewController;
I think there is a case when the observed needs to inform the observer.
I see a similar problem where the UIView in a UIViewController is responding to a situation and it needs to first tell its parent view controller to hide the back button and then upon completion tell the parent view controller that it needs to pop itself off the stack.
I have been trying this with delegates with no success.
I don't understand why this should be a bad idea?
Another easy way is to have your own view class and add a property of the view controller in the view class. Usually the view controller creates the view and that is where the controller can set itself to the property. Basically it is instead of searching around (with a bit of hacking) for the controller, having the controller to set itself to the view - this is simple but makes sense because it is the controller that "controls" the view.
To get the controller of a given view, one can use UIFirstResponder chain.
customView.target(forAction: Selector("viewDidLoad"), withSender: nil)
If your rootViewController is UINavigationViewController, which was set up in AppDelegate class, then
+ (UIViewController *) getNearestViewController:(Class) c {
NSArray *arrVc = [[[[UIApplication sharedApplication] keyWindow] rootViewController] childViewControllers];
for (UIViewController *v in arrVc)
{
if ([v isKindOfClass:c])
{
return v;
}
}
return nil;}
Where c required view controllers class.
USAGE:
RequiredViewController* rvc = [Utilities getNearestViewController:[RequiredViewController class]];
There is no way.
What I do is pass the UIViewController pointer to the UIView (or an appropriate inheritance). I'm sorry I can't help with the IB approach to the problem because I don't believe in IB.
To answer the first commenter: sometimes you do need to know who called you because it determines what you can do. For example with a database you might have read access only or read/write ...

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