I am just looking at ways to access a simple model object (in the MVC sense) from my controller. Right now I am creating the model in the applicationDelegate, and passing it to the controller when I create the controller.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Setup Model
DataModel *tempDataModel = [[DataModel alloc] init];
[self setDataModel:tempDataModel];
[tempDataModel release];
// Setup Controllers
Controller *rootController = [[Controller alloc] initWithModel:[self dataModel]];
UINavigationController *tempNavController = [[UINavigationController alloc] initWithRootViewController:rootController];
[self setNavController:tempNavController];
[rootController release];
[tempNavController release];
[window addSubview:[[self navController] view]];
[window makeKeyAndVisible];
return YES;
}
inside the controller I have:
#property (nonatomic, retain)DataModel *dataModel;
and:
- (id)initWithModel:(id)newModel {
self = [super init];
if(self) {
NSLog(#"%s", __PRETTY_FUNCTION__);
dataModel = [newModel retain];
}
return self;
}
- (void)dealloc {
NSLog(#"%s", __PRETTY_FUNCTION__);
[dataModel release];
[super dealloc];
}
This works fine, but I am just curious if this is ok in terms of MVC and good design. In previous apps I have:
Used a shared instance (Singleton)
Created the model from inside the controller.
Any comments would me much appreciated:
I think this is perfectly good design. The controller is allowed to manipulate the model, so needs a reference to this. I think your current way of injecting the Model instance is better than a singleton approach.
Related
This question is very similar to an existing question asked here UIImagePickerControllerCameraDeviceFront only works every other time I tried the solution presented but it didn't work for me
I have a simplest of a project with two view controllers. In the blue one I am displaying a small UIView with a UIImagePickerController in it. NOTE: I am displaying front facing camera when app is launched.
I hit the next button and go to orange view controller and when I hit the back button and come back to blue view controller the UIImagePickerController flips from Front to rear. I guess the reason is that it thinks its busy and moves to the rear cam. If I keep moving back and forth between the view controllers the camera keeps flipping front, back, front, back, front, back...
Here is my code and screenshots, what am I doing wrong?
In my *.h
#import <UIKit/UIKit.h>
#interface v1ViewController : UIViewController <UIImagePickerControllerDelegate>
{
UIImagePickerController *picpicker;
UIView *controllerView;
}
#property (nonatomic, retain) UIImagePickerController *picpicker;
#property (nonatomic, retain) UIView *controllerView;
#end
In my *.m file (This code is only used when blue colored view controller is displayed)
#import "v1ViewController.h"
#import <MobileCoreServices/UTCoreTypes.h>
#implementation v1ViewController
#synthesize picpicker;
#synthesize controllerView;
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
picpicker = [[UIImagePickerController alloc] init];
picpicker.delegate = self;
picpicker.mediaTypes = [NSArray arrayWithObjects:(NSString *)kUTTypeImage, nil];
picpicker.sourceType = UIImagePickerControllerSourceTypeCamera;
picpicker.cameraDevice = UIImagePickerControllerCameraDeviceFront;
picpicker.cameraCaptureMode = UIImagePickerControllerCameraCaptureModePhoto;
picpicker.showsCameraControls = NO;
picpicker.navigationBarHidden = NO;
picpicker.wantsFullScreenLayout = NO;
controllerView = picpicker.view;
[controllerView setFrame:CGRectMake(35, 31, 250, 250)];
controllerView.alpha = 0.0;
controllerView.transform = CGAffineTransformMakeScale(1.0, 1.0);
[self.view addSubview:controllerView];
[UIView animateWithDuration:0.3
delay:0.0
options:UIViewAnimationOptionCurveLinear
animations:^{
controllerView.alpha = 1.0;
}
completion:nil
];
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[picpicker dismissModalViewControllerAnimated:YES];
}
- (void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
[picpicker dismissModalViewControllerAnimated:YES];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
} else {
return YES;
}
}
#end
You are dismissing the controller in both the viewDidDisappear and viewWillDisappear methods.
That could be the cause of your problem.
Although I do not have a device with a camera available right now to verify this, it seems that you're not dismissing the pickerview controller correctly. The documentation states that you should call dismissModalViewControllerAnimated: on the parent controller in order to dismiss the picker (though, calls to presented controllers will propagate to presenters - so this is not the problem), but in your case you're not displaying the controller modally in the first place so it will not work.
What I would try in this case is to release the picker instead (if not under ARC) and set it to nil (instead of calling [picpicker dismissModalViewControllerAnimated:YES];).
PS. In fact, it seems that there is a bigger problem with your design. Since each button is set to present the other party modally you are not dismissing any of the controllers ever. The controllers just keep stacking on each other. You should either consider to embed them in a navigation controller and have it handle the hierarchy or just set dismissModalViewControllerAnimated: (dismissViewControllerAnimated:completion: on iOS5+) as the action of the second controller's button instead of a modal segue.
This is a very simple issue. I don't know why this happens exactly, but it seems that UIImagePickerController was designed to recreated each time it's needed instead of keeping any reference to it, which seems logical if you think about it. Basically, you need to recreate and reconfigure your picker each time. Below I've pasted some code to give an image of what I mean.
Simple solution:
- (UIImagePickerController *)loadImagePicker {
UIImagePickerController *picpicker = [[UIImagePickerController alloc] init];
picpicker.delegate = self;
picpicker.mediaTypes = [NSArray arrayWithObjects:(NSString *)kUTTypeImage, nil];
picpicker.sourceType = UIImagePickerControllerSourceTypeCamera;
picpicker.cameraDevice = UIImagePickerControllerCameraDeviceFront;
picpicker.cameraCaptureMode = UIImagePickerControllerCameraCaptureModePhoto;
picpicker.showsCameraControls = NO;
picpicker.navigationBarHidden = NO;
picpicker.wantsFullScreenLayout = NO;
return picpicker;
}
and in:
-(void)viewWillAppear:(BOOL)animated{
if(!self.picpicker){
self.picpicker = [self loadImagePicker];
[self.view addSubview: self.picpicker];
}
}
-(void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
[self.picpicker removeFromSuperview];
self.picpicker = nil;
}
My iPhone app badly leaks when flipping back and forth between a main uiviewcontroller and a help uiviewcontroller .
Here is the source of the main view, followed by source of the help view.
MAIN VIEW - FLIP TO HELP.....................
// Changes from operational view to Help view.
- (IBAction)showHelp:(id)sender
{
// End trial mode:
self.stop_trial_if_started;
self.rename_trial_if_edited;
// Switch to trial help:
help_view_context = 0;
HelpView *controller = [[HelpView alloc] initWithNibName:#"HelpView" bundle:nil];
controller.delegate = self;
controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:controller animated:YES];
[controller release];
}
HELP VIEW - INIT.............................
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor viewFlipsideBackgroundColor];
help_scroll.editable = FALSE;
return;
}
HELP - RETURN TO MAIN VIEW.........................
// User clicked the button to return to operational view:
- (IBAction)done:(id)sender {
NSLog(#"help- done");
if( help_view_context == 0 ) {
[self.delegate trial_help_DidFinish:self];
}else{
[self.delegate file_help_DidFinish:self];
}
}
MAIN VIEW - RETURN FROM HELP...............................
// Inits operational view when user changes from Help view back to operational view.
- (void)trial_help_DidFinish:(HelpView *)controller {
NSLog(#"trial_help_DidFinish");
[self dismissModalViewControllerAnimated:YES];
self.init_trial_operation;
}
You are creating a controller with ref count of 1 and a local reference each time showHelp: is called:
HelpView *controller = [[HelpView alloc] initWithNibName:#"HelpView" bundle:nil];
you are losing your reference to it at the end of this method.
You happen to have references to it in done: (self) and *_help_didFinish (controller), but you never release it in either of those locations. Dismissing the controller is fine, but you also have to release it.
(Another option would be to never create a second one, and maintain an iVar to the original.)
You could well be leaking on this line
controller.delegate = self;
What is your property declaration for the delegate. If it's anything other than assign, then you either need to change it (preferred option) or make sure you are releasing it in the dealloc method of HelpView controller.
I'm really new to iPhone programming.
This app is a simple quiz. FirstAppDelegate.m creates an instance of QuizViewController and adds its view to the window.
#import "FirstAppDelegate.h"
#import "ResultViewController.h"
#import "QuizViewController.h"
#implementation FirstAppDelegate
#synthesize window;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions (NSDictionary *)launchOptions {
UIViewController *vc = [[QuizViewController alloc] init];
[window addSubview:[vc view]];
[window makeKeyAndVisible];
[vc release];
return YES;
}
- (void)dealloc {
[window release];
[super dealloc];
}
#end
I thought I could release vc like I do hear since window will retain it (?) but it generated an error :
2011-06-28 23:06:34.190 First[14289:207] -[__NSCFType foo:]: unrecognized selector sent to instance 0x4e1fc90
2011-06-28 23:06:34.193 First[14289:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFType foo:]: unrecognized selector sent to instance 0x4e1fc90'
...so I commented it and now it works fine. But where should I release vc? Here's QuizViewController.h:
#import <UIKit/UIKit.h>
#interface QuizViewController : UIViewController {
IBOutlet UILabel *questionLabel;
IBOutlet UIButton *button1;
IBOutlet UIButton *button2;
IBOutlet UIButton *button3;
int currentQuestionIndex;
int corrects;
NSMutableArray *questions;
NSMutableArray *answers;
NSMutableArray *correctAnswers;
}
- (IBAction)foo:(id)sender;
#end
...and QuizViewController.m:
#import "QuizViewController.h"
#implementation QuizViewController
- (id)init {
NSLog(#"QuizViewController init");
[super initWithNibName:#"QuizViewController" bundle:nil];
questions = [[NSMutableArray alloc] init];
answers = [[NSMutableArray alloc] init];
correctAnswers = [[NSMutableArray alloc] init];
[questions addObject:#"Vad betyder det engelska ordet \"though\"?"];
[answers addObject:#"Tuff"];
[answers addObject:#"Dock"];
[answers addObject:#"Tanke"];
[correctAnswers addObject:#"Dock"];
[questions addObject:#"Vad hette frontpersonen i Popbandet Queen?"];
[answers addObject:#"Pierre Bouviere"];
[answers addObject:#"Freddie Mercury"];
[answers addObject:#"Stevie Wonder"];
[correctAnswers addObject:#"Freddie Mercury"];
return self;
}
- (IBAction)foo:(id)sender {
NSLog(#"foo");
}
- (void)loadView {
NSLog(#"QuizViewController loadView");
[questionLabel setText:[questions objectAtIndex:currentQuestionIndex]];
[button1 setTitle:[answers objectAtIndex:currentQuestionIndex] forState:UIControlStateNormal];
[button2 setTitle:[answers objectAtIndex:currentQuestionIndex + 1] forState:UIControlStateNormal];
[button3 setTitle:[answers objectAtIndex:currentQuestionIndex + 2] forState:UIControlStateNormal];
[super loadView];
}
- (void)viewDidLoad {
NSLog(#"QuizViewController viewDidLoad");
[super viewDidLoad];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (void)viewDidUnload {
[super viewDidUnload];
}
- (void)dealloc {
[super dealloc];
}
#end
You should create an instance variable to hold the VC. The reason you are losing it when you release it is that the window is only retaining the view and not the controller.
I thought I could release vc like I do hear since window will retain it...
Notice that you are adding the view associated to the view controller ([vc view]) to your UIWindow. That object will be retained, not your controller.
You can fix this by defining a variable in your FirstAppDelegate to store the controller there and release it in FirstAppDelegate dealloc.
#interface FirstAppDelegate
.....
#property (nonatomic, retain) QuizViewController* controller;
.....
#end
#implementation FirstAppDelegate
#synthesize window;
#synthesize controller;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions (NSDictionary *)launchOptions {
self.controller = [[QuizViewController alloc] init] autorelease];
[window addSubview:[vc view]];
[window makeKeyAndVisible];
return YES;
}
- (void)dealloc {
....
[controller release]; controller = nil;
....
}
The views/windows do retain their child views, the view controllers retain their views, but the views don't retain their controllers. It's a "one-way" relationship, a clear has-a. This also comes in handy to prevent retain cycles.
You probably want to save the controller in an ivar in the class you alloc/init it, and release it in dealloc or when you pull the view from screen.
View controllers often get retained by other view controllers, i.e. when you push them onto a navigation stack, or put them in tabs.
If you don't mind dropping support for iOS 3.0/3.1/3.2, you can use the UIWindow.rootViewController property:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions (NSDictionary *)launchOptions {
UIViewController *vc = [[[QuizViewController alloc] init] autorelease];
window.rootViewController = vc;
[window makeKeyAndVisible];
return YES;
}
I am just curious with regards to the correct way to create a view controller programatically. When I compile this code with the static analyser I get a leak (as you would expect) from the alloc. Should I just leave it as it needs to stay until the app exits anyways, or is there a cleaner way?
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
NSLog(#"UIApplication application:");
RectViewController *myController = [[RectViewController alloc] init];
[window addSubview:[myController view]];
[window makeKeyAndVisible];
return YES;
}
cheers Gary
In this case, keep a reference to your view controller as an instance variable on the AppDelegate and release it in the AppDelegate's dealloc method.
#interface AppDelegate : NSObject {
// ...
RectViewController *myController;
}
// ...
#end
#implementation AppDelegate
// ...
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
NSLog(#"UIApplication application:");
myController = [[RectViewController alloc] init];
[window addSubview:[myController view]];
[window makeKeyAndVisible];
return YES;
}
- (void) dealloc {
// ...
[myController release];
[super dealloc];
}
// ...
#end
Keep a reference to the view controller in you app delegate (instance, property, synthesize and release in dealloc).
And then instantiate it like this:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
NSLog(#"UIApplication application:");
RectViewController *rootControllerTemp = [RectViewController new];
self.rootController = rootControllerTemp;
[rootControllerTemp release];
[window addSubview:[self.rootController view]];
[window makeKeyAndVisible];
return YES;
}
It is in My view controller
-(void)doctorsListAction
{
if(isFirst == YES)
{
[self getDoctorsListController];
[[self navigationController] presentModalViewController:doctorListViewNavigationController animated:YES];
[doctorListViewController release];
}
}
-(void)getDoctorsListController
{
//DoctorListViewController *doctorListViewController=[[[DoctorListViewController alloc]initWithNibName:nil bundle:nil]autorelease];
doctorListViewController=[[DoctorListViewController alloc]init];
doctorListViewNavigationController=[[UINavigationController alloc]initWithRootViewController:doctorListViewController];
doctorListViewController.doctorList=doctorList;
doctorListViewNavigationController.navigationBar.barStyle= UIBarStyleBlackOpaque;
[doctorListViewController release];
}
It is in DoctorListViewContrller
-(void)closeAction
{
printf("\n hai i am in close action*******************************");
//[doctorList release];
//[myTableView release];
//myTableView=nil;
printf("\n myTableView retainCount :%d",[myTableView retainCount]);
[[self navigationController] dismissModalViewControllerAnimated:YES];
}
//this method is not called I don't know why if it not called i will get memory issues
- (void)dealloc
{
printf("\n hai i am in dealloc of Doctor list view contrller");
[doctorList release];
[myTableView release];
myTableView=nil;
[super dealloc];
}
this method is not called I don't know
why if it not called i will get memory
issues
When exactly dealloc gets called (i.e. when the object is deallocated) shouldn't really matter to you. What matters is that you pair up each alloc with a release/autorelease. Which you are likely not doing.
The above code doesn't read very well and looks a bit "Java"-ish. Your "get" method doesn't actually return anything, which looks strange. But you normally wouldn't name a method "get___" anyway.
You're probably leaking memory in your getDoctorsListController method on this line:
doctorListViewNavigationController=[[UINavigationController alloc]initWithRootViewController:doctorListViewController];
Since you didn't define doctorListViewNavigationController in this method, and I assume you posted code that compiles, it is either a member (although not necessarily a property) of your class or a static variable somewhere. Which means it could already be pointing to an object. Which means when you assign a new alloc'ed object to it, the old one is lost (leaked).
Here's how you should refactor it.
- (void)doctorsListAction
{
if (isFirst == YES)
{
[self showDoctorsList];
}
}
- (void)showDoctorsList
{
DoctorListViewController* doctorListViewController = [[DoctorListViewController alloc] initWithNibName:nil bundle:nil];
doctorListViewController.doctorList = doctorList;
UINavigationController* navController = [[UINavigationController alloc] initWithRootViewController:doctorListViewController];
navController.navigationBar.barStyle = UIBarStyleBlackOpaque;
[self.navigationController presentModalViewController:navController animated:YES];
[navController release];
[doctorListViewController release];
}
There might be a lot of other objects 'behind the scenes' that want to keep the DoctorListViewController around. If you just balance out your retains and releases, you should be ok.
Also in -(void)doctorsListAction, shouldn't [doctorListViewController release]; be [doctorListViewNavigationController release]; instead?