Why does this code cause a memory leak? - ios

I execute this code in my applicationDidBecomeActive callback.
- (void)applicationDidBecomeActive:(UIApplication *)application{
[self showMainWindow];
}
- (void) showMainWindow{
PushNotificationTabBarController *pushNotificationTabBarController = [[PushNotificationTabBarController alloc] initWithNibName:#"PushNotificationTabBarController" bundle:nil];
self.viewDeckController.centerController =
pushNotificationTabBarController; // registered for Notification via addObserver...
}
The setter is defined like this:
#property (nonatomic, strong) IBOutlet UIViewController* centerController;
IIViewDeckController property in my AppDelegate:
#property (strong, nonatomic) IIViewDeckController *viewDeckController;
I found out that I have 2 PushNotificationTabBarController objects when I close and re-enter the app, with no reference to one of them, like a memory leak. However I dont understand why this code is causing it because to me it seems ok. I'm using ARC.

Before setting pushNotificationTabBarController check for self.viewDeckController.centerController object. If it exists, release and assigned to nil and assign new object of 'pushNotificationTabBarController'
id controller = self.viewDeckController.centerController;
if (controller) {
[controller release];
controller = nil;
}
self.viewDeckController.centerController = pushNotificationTabBarController;

Related

xctest - how to test if a new view loads on a button press

Just started xcode 5 and xctest. How do I test that a view loads on button press. I have programatically added method that gets called when the rightBarButtonItem is clicked
action:#selector(onSettingsButton)
and in onSettingsButton
-(void) onSettingsButton{
SettingsViewController *svc = [[SettingsViewController alloc] init];
[self.navigationController pushViewController:svc animated:YES];
}
How to write xctest to ensure SettingsViewController brings up the Settings view? Thank you.
You need an interaction test — that is, a test that checks interactions between objects. In this case, you want to test that -pushViewController:animated: is called on the navigation controller with a SettingsViewController. So we want to put a mock object into self.navigationController which we can ask, "Were you called as expected?"
I'll assume a simple name for the class: MyView.
The way I'd do this by hand is to Subclass and Override navigationController. So in my test code, I'd do something like this:
#interface TestableMyView : MyView
#property (nonatomic, strong) id mockNavigationController;
#end
#implementation TestableMyView
- (UINavigationController *)navigationController
{
return mockNavigationController;
}
#end
Now instead of creating a MyView, the test will create a TestableMyView and set its mockNavigationController property.
This mock can be anything, as long as it responds to -pushViewController:animated: and records the arguments. Here's a simple example, by hand:
#interface MockNavigationController : NSObject
#property (nonatomic) int pushViewControllerCount;
#property (nonatomic, strong) UIViewController *pushedViewController;
#property (nonatomic) BOOL wasPushViewControllerAnimated;
#end
#implementation MockNavigationController
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
self.pushViewControllerCount += 1;
self.pushedViewController = viewController;
self.wasPushViewControllerAnimated = animated;
}
#end
Finally, here's a test:
- (void)testOnSettingsButton_ShouldPushSettingsViewController
{
// given
MockNavigationController *mockNav = [[MockNavigationController alloc] init];
TestableMyView *sut = [[TestableMyView alloc] init];
sut.mockNavigationController = mockNav;
// when
[sut onSettingsButton];
// then
XCTAssertEquals(1, mockNav.pushViewControllerCount);
XCTAssertTrue([mockNav.pushedViewController isKindOfClass:[SettingsViewController class]]);
}
These things can be simplified by using mock object frameworks such as OCMock, OCMockito, or Kiwi's mocking. But I think it helps to start by hand first, so that you understand the concepts. Then choose the tools that help. And if you know how to do it by hand, you'll never say, "Mocking framework X doesn't do what I need! I'm stuck!"
Found one way. Maybe there are others ..
- (void)testSettingsViewShowsWhenSettingsButtonIsClicked{
[self.tipViewController onSettingsButton];
id temp = self.tipViewController.navigationController.visibleViewController;
XCTAssertEqual([temp class], [SettingsViewController class], #"Current controller should be Settings view controller");
}
First call the onSettingsButton, which is the same as clicking the button, but not really. Maybe it's okay for this simple test case? How to simulate the actual press?
Then get the current view from the tipviewcontoller which is the rootview of the app and check that it is a SettingsViewController.

Best way to safely clear data in a singleton?

I'm using a singleton called CSAppData to store data for my iPhone app. I'm storing an object called CSInbox in the singleton. When I logout of my app, I want to clear the data for that object.
Here is my singleton code, including the method for clearing the data:
- (id)init {
self = [super init];
if (self)
{
self.inbox = [[CSInbox alloc] init];
}
return self;
}
+ (CSAppData *)appData {
static CSAppData * appDataInstance;
#synchronized(self) {
if(!appDataInstance) {
appDataInstance = [[CSAppData alloc] init];
}
}
return appDataInstance;
}
+(void) clearData {
CSAppData *appData = [CSAppData appData];
appData.inbox = [[CSInbox alloc] init];
}
However, in one of my view controllers, in the initWithCoder method, I'm storing the inbox variable:
-(id) initWithCoder:(NSCoder *)aDecoder {
self = [super initWithCoder:aDecoder];
if(self) {
self.inbox = [[CSAppData appData] inbox];
}
return self;
}
So, when the app logs out and the clearData method is called, the view controller is still pointing to the old CSInbox object. And even though I am initializing a new view controller and setting it to the root view controller (in the AppDelegate), like this:
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:#"MainStoryboard" bundle:nil];
MainTabControllerViewController *viewController = (MainTabControllerViewController *)[storyboard instantiateViewControllerWithIdentifier:#"mainView"];
[self.window setRootViewController:viewController];
The one child view controller that has the CSInbox is never reinitialized, and is still pointing to that old CSInbox object. (I'm not sure why this is happening.)
So, what is the best way to solve this?
Change the clearData method in the singleton to just reset the properties of the CSInbox object, rather than alloc and init and new one?
Move the self.inbox = [[CSAppData alloc] init]; to the viewDidLoad in the view controller class so it gets set properly upon the second login?
Change the logout function in the AppDelegate so that the root view controller and all other view controllers are released, so they will reinitialize upon the second login?
I'm leaning toward #1 or #3...
As requested, here is CSInbox.h:
#interface CSInbox : NSObject
#property (nonatomic,strong) NSMutableArray *threads;
#property (nonatomic, assign) NSInteger newCount;
#property (nonatomic,strong) NSDate *lastUpdate;
-(void) setThreadsFromJSON:(NSDictionary *)json;
#end
And here is CSInboxViewController.h:
#interface CSInboxViewController : UITableViewController <UITableViewDataSource, UITableViewDelegate, CSThreadViewControllerDelegate>
#property (strong, nonatomic) IBOutlet UITableView *inboxTableView;
#property (strong,nonatomic) CSInbox *inbox;
#end
And CSAppData.h:
#interface CSAppData : NSObject {
CSInbox *inbox;
}
#property(nonatomic,strong) CSInbox *inbox;
+ (CSAppData *)appData;
+ (void)clearData;
#end
I think the answer lies not in destroying the singleton object and recreating it, but to actually clear the instance variables within that singleton object.
You don't show the declaration of [CSAppData inbox], but if it's an NSMutableArray, for example, then you can clear that, and any existing references to the singleton object can remain:
+(void) clearData {
CSAppData *appData = [CSAppData appData];
[appData.inbox removeAllObjects];
}
One way to handle this, complying with the spirit of using a singleton, is having your view controllers access directly your singleton inbox, i.e.: [CSAppData appData].inbox instead of self.inbox. This is a bit wordier, but it would "magically" fix your issue.
If that is not acceptable to you, I would go with option #1 of those you list. Even better, I would make the inbox in the singleton a singleton itself, or make sure it is never replaced by another instance.
EDIT:
Another approach you have, is using KVO in your controller so that it gets notified when the inbox object has changed. Don't know if it is quite worth it, but could be used.

Add objects to an NSMutableArray in my base view controller from a second view controller, ios

I have been searching all morning how to do this. I have 2 View Controllers. From the root View Controller (ViewControllerA - which is a table view controller) you can go push to the second view controller (ViewControllerB).
In the ViewControllerB, there are two fields: contacts & textBody. When the user is done they can click on "Add". This will then go back to ViewControllerA. What I am trying to do now, is for every time that process occurs, all the information from ViewControllerB the user just added goes into a cell in ViewControllerA. The user can then add as many cells as they like.
What I can't do however, is get the information across the view controllers. I have been looking all morning at using the app delegate, singletons??, protocols, sharing properties, etc! But I am still stuck.
What I want to do, but can't, is for every time the user clicks "Add" on ViewControllerB, contacts & texts are put into an array. This array is then put into another array which holds all the smaller arrays which the user has created? If you have an ideas, or links to similar/sample code or tutorials, that would be much appreciated!
Try this using the delegate method as follows
Download Sample Project with XIBs
Download Sample Project With Storyboard
ParentViewController.h
#import <UIKit/UIKit.h>
#interface ParentViewController : UIViewController {
NSMutableArray *dataArray;
}
- (void)passData:(NSMutableArray *)array;
#end
ParentViewController.m
#import "ParentViewController.h"
#import "ChildViewController.h"
#implementation ParentViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Initialise the mutable array.
dataArray = [[NSMutableArray alloc] init];
}
- (IBAction)btnGoToSecondView:(id)sender {
ChildViewController *secondVC = [[ChildViewController alloc] initWithNibName:#"ChildViewController" bundle:nil];
secondVC.delegate = self;
[self presentViewController:secondVC animated:YES completion:nil];
}
- (void)passData:(NSMutableArray *)array {
[dataArray addObject:array];
NSLog(#"Data Passed = %#",dataArray);
}
#end
ChildViewController.h
#import <UIKit/UIKit.h>
#import "ParentViewController.h"
#class ParentViewController;
#interface ChildViewController : UIViewController {
NSMutableArray *tempArray;
}
#property (strong, nonatomic) IBOutlet UITextField *txtContact;
#property (strong, nonatomic) IBOutlet UITextField *txtTextBody;
#property(nonatomic, assign) ParentViewController *delegate;
#end
ChildViewController.m
#implementation ChildViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Initialise the mutable array.
tempArray = [[NSMutableArray alloc] init];
}
- (IBAction)btnPassDataBack:(id)sender {
if([self.delegate respondsToSelector:#selector(passData:)]) {
[tempArray addObject:_txtContact.text];
[tempArray addObject:_txtTextBody.text];
[self.delegate passData:tempArray];
}
[self dismissViewControllerAnimated:YES completion:nil];
}
- (void)viewDidUnload {
[self setTxtContact:nil];
[self setTxtTextBody:nil];
[super viewDidUnload];
}
#end
With Storyboard
If you are using storyboard then create a ParentViewController segue ChildViewController and give it a identifier in my sample it showChildView
Then use the following code to set the delegate
// Calling the segue to go to the child view and setting up the delegate.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"showChildView"]) {
ChildViewController *childVC = segue.destinationViewController;
childVC.delegate = self;
}
}
Then to dismiss back to the ParentViewController use the following code (from my sample)
- (IBAction)btnPassDataBack:(id)sender {
if([self.delegate respondsToSelector:#selector(passData:)]) {
[tempArray addObject:_txtContact.text];
[tempArray addObject:_txtTextBody.text];
[self.delegate passData:tempArray];
}
[self.navigationController popToRootViewControllerAnimated:YES];
}
I would recommend using a singleton instance of your NSMutableDictionary as they have bailed me out of your exact situation multiple times (including custom frameworks and UITabBarControllers). Here is an example I'm currently using to implement a singleton. This methodology is also ARC-safe as well
mySingleton.h
#import <Foundation/Foundation.h>
#interface mySingleton : NSObject {
}
+ (NSMutableDictionary *) myMutableDict;
#end
mySingleton.m
#import "mySingleton.h"
#implementation mySingleton
+ (NSMutableDictionary *)myMutableDict
{
static NSMutableDictionary *singletonInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
singletonInstance = [[NSMutableDictionary alloc]init];
});
return singletonInstance;
}
#end
As long as you include mySingleton.h in all of your view controllers you can access the data via [mySingleton myMutableDict]. For example: [[mySingleton myMutableDict] setObject:myObject forKey:myKey];
Good luck!
If the information is really "global" - it has only one instance across the whole app - then you should create a singleton as DB80Buckeye suggested.
If the information is something that truly belongs to ViewController1 and you want it to be modified in ViewController2 (ie ViewController2 is really part of ViewController1, it just happens to be on another screen), then you should pass that as part of the constructor of ViewController2.
-(void)view_controller_1_that_push_view_controller_2_onto_the_stack {
ViewController2* vc2 = [[ViewController2 alloc] initWithInformation:your_information];
[self.navigationController pushViewController:vc2 animated:YES];
}
#interface ViewController2
-(id)initWithInformation:(YourInformationClass*)info;
#end
Another way is to use notifications.
There are two ways to go here. The standard pattern for doing this is delegation. You don't need a singleton. ViewControllerA manages and lists your data. ViewControllerB doesn't need to know anything about all of that data so there's no reason to expose it via a singleton, etc.
Create a delegate protocol in ViewControllerB's header file. Something like this:
#protocol ViewControllerBDelegate
- (void)addContact:(NSString *)contact withBody:(NSString *)textBody;
#end
Now, specify that ViewControllerA will implement the delegate protocol in its header:
#interface ViewControllerA : UIViewController <ViewControllerBDelegate>
Don't forget to import ViewControllerB.h at the top of ViewControllerA's header.
In ViewControllerA's implementation, implement the delegate method you specified in the protocol:
- (void)addContact:(NSString *)contact withBody:(NSString *)textBody {
[self.someArray addObject:[[SomeObject alloc] initWithContact:contact body:textBody]];
[self.tableView reloadData];
}
That's obviously just an example -- not sure how you're managing your data structure and it's probably better to insert the cell someplace that makes sense.
Declare a delegate reference in ViewControllerB's header:
#property (weak, nonatomic) id<ViewControllerBDelegate> delegate;
When you present ViewControllerB, set ViewControllerA as the delegate.
ViewControllerB *b = [[ViewControllerB alloc] init...];
b.delegate = self;
In the selector triggered by the add button in ViewControllerB, call back on the delegate before popping the view controller off the navigation stack:
[self.delegate addContact:contact withBody:text];
where contact and text are the values the user entered.
One could also use a block instead of a delegate but the principle is the same -- have the second view controller only be responsible for taking input, in your case, and pass it back to the view controller managing the data.
Alternatively for delegate suggest using the following:
ViewControllerA.h:
#property (nonatomic, strong) ViewControllerB* viewControllerB;
In ViewControllerA.m
if (!self.viewControllerB)
{
self.viewControllerB = [[ViewControllerB alloc] initWithNibName: #"ViewControllerBr" bundle: nil];
}
[self.navigationController pushViewController: self.viewControllerB
animated: YES];
...
- (void) viewWillAppear: (BOOL) animated
if (self.viewControllerB)
{
NSString* contact = self.viewControllerB.contact;
NSLog(#"%#", contact);
}
...

Modifying UIButton's alpha property from another class

I'm trying to change the alpha of an UIButton from another class. The function that is called in set the alpha property of my UIButton is actually called because I've put a NSLog there and I can see how it works. I'd be thankful if you could give me any suggestion.
Here's my current code.
ViewController.h
- (void) setAlphaToButton;
#property (strong, nonatomic) IBOutlet UIButton *myButton;
ViewController.m
#synthesize myButton;
- (void) setAlphaToButton {
myButton.alpha = 0.5;
NSLog(#"Alpha set");
}
ImageViewSubclass.m
- (void) tapDetected:(UITapGestureRecognizer *)tapRecognizer {
ViewController *VC = [[ViewController alloc] init];
[VC setAlphaToButton];
}
And when the image view is pressed, in my console I get: Alpha set. And the button doesn't change.
In your code, an instance of ViewController is alloced and inited, and the method setAlphaToButton is called on it. Then the view controller is released because you have no object retaining it. That's why you don't see any effect; the ViewController instance you call the method on never appears on screen.
It's not clear how your code is supposed to work; do you have an instance of ViewController in existence when tapDetected is called? If this is the case, and this is the ViewController whose button you want to alter the alpha of, then you need to have a reference to that instance of ViewController and call setAlphaToButton on it.
Your view is not loaded at the moment you trying to set alpha! You need to call this method after your viewDidLoad fired. You can force it by calling view, but it's kind of hackand not recommended!
MyViewController *vc = [MyViewController new];
vc.view; // this string will force view loading
[vc setAlphaToButton];
Add a property of uiviewcontroller class in imageviewsubclass as
ImageViewSubclass.h
#propery (nonatomic, retain) uiviewController *parent;
ImageViewSubclass.m
#synthesize parent;
And initialize it with "self" in view controller class when initalize object of imageviewsubclass and add on the view like
ImageViewsubclass *oneObj = [ImageViewsubClass alloc] init];
oneOBj.parent = self;
do the same for all objects of ImageviewsubClass objects.
and in
- (void) tapDetected:(UITapGestureRecognizer *)tapRecognizer {
[parent setAlphaToButton];
}

Using my own delegate

I´m having problems declarating my own delegate. Well...thats not exactly true: i have it declarated and, when i build the project, the compiler reports no issues. I declarated it in this way:
I made a file (enviarDatos.h) for declare the protocol:
#protocol enviarDatos <NSObject>
- (void)addItemViewController:(NSMutableArray *)item;
#end
In the Vista2.h (ViewController) file I imported the file enviarDatos.h and declared a property:
#property (nonatomic, weak) id <enviarDatos> delegare;
In the Vista2.m (ViewController) file I use the protocol method:
#interface ViewController : UIViewController <enviarDatos> {
And, finally, in the ViewController.m file I implement the delegates method:
- (void)addItemViewController:(NSMutableArray *)ar {
origen = ar;
}
Does anyone see something wrong? the code of the last function its never executing.
Thanks for your help.
EDIT:
What i need is to change an array in ViewController from Vista2 (another viewcontroller)
Then create delegate property in next view(child view) & set it to self in parent view while pushing or showing child view.
ParentView.m
1.Implement protocol methods
- (void)addItemViewController:(NSMutableArray *)ar
{
origen = ar;
}
2.While showing child view
ChildViewController *child = [[ChildViewController alloc] init];
child.delegate = self;
//present child view
ChildView.h
#property (nonatomic, weak) id <enviarDatos> delegare;
ChildView.m
-(void) anyMethod
{
if([self.delegate respondsToSelector:#selector(addItemViewController:)])
{
[self.delegate addItemViewController:mutableArray];
}
}
Ah, it looks like you are declaring the delegate property in the wrong place.
You should declare the property delegate in enviarDatos.h.
#property (nonatomic, weak) id <enviarDatos> delegate;
Then in Vista2.m you will do something like this...
EnviarDatos *myObject = [[EnviarDatos alloc] init];
myObject.delegate = self;
This then sets up the EnviarDatos object and assigns the Vista2 object as the delegate.
Now, in EnviarDatos.m you can run...
[self.delegate addItemViewController:someObjectArray];
And this will then run that code in the Vista2 object.
Delegates are used for calling back to objects that create them (or some other objects). If you create an object and then want to run a method in it then you won't need a delegate.
Can you say at what condition addItemViewController is invoked?
You seem to be on the right track, but are you sure you are setting the delegate as
[yourObject setDelegate: self];
Have you tried debugging it? Does the debugger pause at addItemViewController if you set a breakpoint there? Can you confirm the delegate is not null inside the method? I may post some code but your seems to be right except for the assigning of delegate, I think you should check it.

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