I am using the nav controller and pushing another view into the stack and setting a variable too. While trying to access the variable I get EXEC_BAD_ACCESS :(
Here's the code (I am not using any NIB) :
#import <UIKit/UIKit.h>
#interface detailedView : UIViewController {
NSString *movieName2;
}
#property (nonatomic, retain) NSString *movieName2;
#end
and
#import "detailedView.h"
#implementation detailedView
#synthesize movieName2;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
-(void) viewDidAppear:(BOOL)animated
{
self.view=[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
self.view.frame=CGRectMake(213, 300, 355, 315);
self.view.backgroundColor=[[UIColor alloc] initWithPatternImage:[UIImage imageNamed:#"black.png"]];
self.title=self.movieName2;
NSLog(#"%#",movieName2);
}
Relevant code in the caller function :
detailedView *details;
#property (nonatomic, retain) detailedView *details;
//properly synthesized and released
-(void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"Did Reach inside...");
status=1;
self.title=#"Back";
details.movieName2=self.movieName;
NSLog(#"```");
NSLog(#"2nd VC %# sdfsdf",details.movieName2); //Getting the ERROR here
NSLog(#"1st VC %# wrewrw",self.movieName);
//viewerSearch *viewerSearchController=[[viewerSearch alloc] init];
[[self navigationController] pushViewController:details animated:NO];
}
init:
details=[[detailedView alloc] init];
//movieName is a NSString and has #property(nonatomic,copy)
When an app crashes, there will be a crash log or you'll be able to get a backtrace from the debugger. Always post that.
Also -- class names should always start with a capital letter.
Try Build and Analyze; make sure your memory management is correct.
Then turn on Zombie detection once you fix any build and analyze found problems.
Based on a test by calling a retain on a alloc-init-released NSString and then following it up by logging it, I think your problem is that self.movieName is deallocated. Please check whether the memory management rules have been properly followed with regards to self.movieName.
On a side note, if you are not using a NIB for detailedView then you should create the view in loadView and not viewDidAppear: as you seem to be doing. viewWillAppear: only if the view exists, right? I suggest you move the related code from viewDidAppear: to loadView.
You should always copy strings instead of retaining them.
So changing
#property (nonatomic, retain) NSString *movieName2;
to
#property (nonatomic, copy) NSString *movieName2;
will probably fix your problem.
Also, if you create the value in self.movieName with #"something", do not release the value.
Related
Manual memory management is used. The following code runs well and no crash occurs. But there is no -(void)dealloc method. Is this code wrong? Should I add -(void)dealloc?
MyClass.h
#import <UIKit/UIKit.h>
#interface MyClass : NSObject {
#private
BOOL flag;
UIView *view;
UILabel *label;
UIButton *button;
UITabBar *tabBar;
UIWebView *webView;
UIImageView *imageView;
}
#property (nonatomic, retain) UIView *view;
#property (nonatomic, retain) UILabel *label;
#property (nonatomic, retain) UIButton *button;
#property (nonatomic, retain) UITabBar *tabBar;
#property (nonatomic, retain) UIWebView *webView;
#end
MyClass.m
#import "MyClass.h"
#implementation MyClass
#synthesize view;
#synthesize label;
#synthesize button;
#synthesize tabBar;
#synthesize webView;
- (id)init {
self = [super init];
if (self) {
// Initialization code
// Among other code,
imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
}
return self;
}
// Other methods here.
// But -(void)dealloc is not overridden here in the MyClass.m
#end
If we must add -(void)dealloc for the above code, should it be like this:
Overridden -(void)dealloc
-(void)dealloc {
[view release];
[label release];
[button release];
[tabBar release];
[webView release];
[super dealloc];
}
Update 1
#synthesize added, see above.
Update 2
Didn't put this into another post because this seems rather related issue:
See the above MyClass.m/.h, there is a private ivar (not sure it should be called ivar or field here) UIImageView *imageView;, it has no property for it, no #synthesize, initialization given there, how can we dealloc it? Also [imageView release]; in -(void)dealloc?
Update 3
Do we have to check availability before releasing ivars? That is, instead of [view release];, use this:
if (nil != view) {
[view release];
}
Yes. You need to implement dealloc.
You dealloc will look like :
-(void)dealloc {
[_view release];
[_label release];
[_button release];
[_tabBar release];
[_webView release];
[super dealloc];
}
Any retained/copy property should be released on dealloc.
Your iVar have no meaning. They do not have the same information as the properties, so you can remove your iVars.
If you want your properties to be backed up by your iVars you should #synthesize them like:
#synthesize view = view;
#synthesize label = label;
#synthesize button = button;
#synthesize tabBar = tabBar;
#synthesize webView = webView;
As you are not using ARC, your code (including the dealloc method) is correct, however you are missing the #synthesize statement in the implementation for the properties to work:
#implementation MyClass
// this will synthesize the getters and setters
#synthesize view, label, button, tabBar, webView;
- (id)init {
self = [super init];
if (self) {
// Initialization code
}
return self;
}
// Other methods here.
-(void)dealloc {
[view release];
[label release];
[button release];
[tabBar release];
[webView release];
[super dealloc];
}
#end
While Daniel's answer is correct in addressing your question, it does not cover what you should do.
This is how your code would be written in a modern world:
turn on ARC. Especially if you are learning or this is your first project. There is no reason to not use ARC. Learning manual-retain-release is valuable, but not critical at this time as the tools do a very good job of providing analysis of when ARC based patterns are leaking memory (either the analyzer or using Instruments, both of which you would need to use under MRR and neither of which work as well under MRR).
Don't use #synthesize and don't declare iVars (and certainly don't declare iVars in your .h file). Let the compiler autho-synthesize the _ prefixed ivars automatically. The _ prefix has the added advantage of disallowing you from accidentally directly accessing an ivar in code. I.e. self.foo vs. foo; the second won't compile.
Or to translate into code:
#interface MyClass : NSObject
#property (nonatomic, retain) UIView *view;
#property (nonatomic, retain) UILabel *label;
#property (nonatomic, retain) UIButton *button;
#property (nonatomic, retain) UITabBar *tabBar;
#property (nonatomic, retain) UIWebView *webView;
#end
And:
#implementation MyClass
{
BOOL _flag;
UIImageView *_imageView;
}
- (id)init {
self = [super init];
if (self) {
_imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
}
return self;
}
// no -dealloc
#end
Note that I declared _imageView as an instance variable that will be compatible with the obvious imageView #property should you need to refactor your class later to make that externally available.
If you realy must use manual retain-release, then add a -dealloc method that calls -release on all the ivars. I.e.[_view release];, [_imageView release];, etc...
Don't get what you mean by "Note that I declared _imageView as an
instance variable that will be compatible with the obvious imageView
#property should you need to refactor your class later to make that
externally available."
If you were to decide that _imageView needs to be accessible to other objects, then you would delete the iVar declaration and add:
#property(nonatomic, retain) UIImageView *imageView;
The compilers automatic synthesis would create an instance variable named _imageView automatically and none of the rest of your code would have to change.
Do we have to make sure an ivar is not nil before releasing it in
dealloc method? (See Update 3 above.)
No. In Objective-C, nil eats messages. That is, [nil release]; is perfectly valid and does absolutely nothing at runtime.
In your code the BOOL flag; has disappeared. Do we have make a
property for BOOL flag;, that is, #property BOOL flag;? Or all we have
to do is just placing a private field in the MyClass.h as #private
BOOL flag; up there in my original question?
I forgot it. You could create a property for it. Or you could declare _flag as an iVar next to _imageView as I've done above.
Most importantly, there is no longer any reason (save for a very rare case that is generally too be avoided) to declare instance variables in your .h.
I'm trying to follow the suggestion in the accepted answer at How to intercept click on link in UITextView? , but I've managed to get myself very confused, partially because I don't understand delegation very well, and by now I've added and deleted so many things I have no idea what's going on.
Here's GHFeedback.h:
#import <UIKit/UIKit.h>
#import "GHApplicationSubclassed.h"
#interface GHFeedback : UIViewController <UIApplicationDelegate>
#property (nonatomic, strong) UITextView *feedbackInstructions;
#property (nonatomic, strong) GHApplicationSubclassed *ghAppSub;
#end
Here's GHFeedback.m:
#import "GHFeedback.h"
#import <MessageUI/MessageUI.h>
#import "GHApplicationSubclassed.h"
#interface GHFeedback () <UIApplicationDelegate, MFMailComposeViewControllerDelegate>
#end
#implementation GHFeedback
#synthesize feedbackInstructions, ghAppSub;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
self.ghAppSub.delegate=self;
}
return self;
}
-(void)openURL:(NSURL *)url //This is the method I'm trying to add--the text set for self.feedbackInstructions in IB contains an email address, and I want a subject line to appear automatically if the user sends an email.
{
MFMailComposeViewController *mailer = [[MFMailComposeViewController alloc] init];
mailer.mailComposeDelegate = self;
[mailer setSubject:#"feedback on Haiku"];
[self presentViewController:mailer animated:YES completion:NULL];
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
Here's GHApplicationSubclassed.h:
#import <UIKit/UIKit.h>
#interface GHApplicationSubclassed : UIApplication <UIApplicationDelegate>
#property (nonatomic, strong) GHApplicationSubclassed *appli;
#end
Here's GHApplicationSubclassed.m:
#import "GHApplicationSubclassed.h"
#implementation GHApplicationSubclassed
#synthesize appli;
-(BOOL)openURL:(NSURL *)url
{
if ([self.delegate openURL:url]) //This line gets an error, "no known instance method for selector 'openURL'
return YES;
else
return [super openURL:url];
}
#end
I'd love explicit instructions on how to fix this. (By "explicit" I mean that, rather than saying something like, "then implement the delegate method," you could say something like, "then add this method to GHFeedback.m: -(void)openURL {[actual methods, etc., etc.]}.
Thanks so much for your help.
EDIT: What I want to happen is this.
There's a UITextView displayed in the view controller for GHFeedback that says, "if you have any questions/problems with the app, please email me," and then gives my email address. Right now, when the user presses that email address, the iOS Mail program opens an empty draft email. I would like to give the draft email that opens an automatic subject line of "feedback on Haiku."
if ([self.delegate openURL:url])
The return type of openURL: is void, so there is actually nothing to check in this if-statement.
maybe you want to use
if ([(GHFeedback *)self.delegate respondsToSelector:#selector(openURL:)]{
[(GHFeedback *)self.delegate openURL:url];
return YES;
}
if the correct openURL: still wont get fired, the self.delegate must be nil.
I'm learning ObjC and cocoa dev and have come across a real 'stumper'. Having exhausted Google, I respectfully adorn my desperation hat and present to you:
A class and a view controller:
The class 'Content Window' imports a viewcontroller instance and places it in a window:
ContentWindow.h
#import <Foundation/Foundation.h>
#import <WebKit/WebView.h>
#import "ContentViewController.h"
#interface ContentWindow : NSWindow{
ContentViewController* viewController;
}
#property IBOutlet ContentViewController* viewController;
-(NSWindow *) newWindow;
#end
ContentWindow.m
#import "ContentWindow.h"
#implementation ContentWindow
#synthesize viewController;
-(NSWindow *) newWindow{
//Builds the window as 'window' and displays it successfully here
//... [code redacted for brevity]
// Build view
viewController = [[ContentViewController alloc] initWithNibName:#"ContentViewController" bundle:nil];
[window setContentView: viewController.view];
NSString *urlString = #"http://www.google.com";
[[viewController.webView mainFrame] loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:urlString]]];
[viewController.title setStringValue:#"my title"];
}
#end
I am attempting to do two things with the interface:
[viewController.title setStringValue:#"my title"];
This successfully sets the view element 'title' to "my title".
[[viewController.webView mainFrame] loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:urlString]]];
This, however, throws the error:
Receiver type 'WebFrame' for instance message is a forward declaration.
and underlines in red the section of the line:
viewController.webView mainFrame
My view controller is as follows:
ContentViewController.h
#import <Cocoa/Cocoa.h>
#import <WebKit/WebView.h>
#interface ContentViewController : NSViewController {
IBOutlet NSTextField *title;
IBOutlet WebView *webView;
}
#property IBOutlet WebView *webView;
#property IBOutlet NSTextField *title;
#end
ContentViewController.m
#import "ContentViewController.h"
#interface ContentViewController ()
#end
#implementation ContentViewController
#synthesize title, webView;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
}
return self;
}
#end
Finally to use this class, I am instantiating a content window from my AppDelegate class with
contentWindow = [[ContentWindow new] newWindow];
Having imported ContentWindow.h into AppDelegate.h and having set:
__strong NSWindow * contentWindow
as an AppDelegate synthesised instance variable.
I have linked both items in IB (definitely!) I have also added Webkit foundation to my project, which was suggested in another thread.
I can't for the life of me understand what is going on. I know that the logical answer is to put down Xcode and pick up the 'Learn Xcode and Objective c' book (with a bookmark about half way through where I was arrogant enough to think I'd learned enough to try something out), but before I do that, on the off-chance:
Could anyone help?
Thanks as always, AtFPt.
Usually this error message means, that the type of a class is not know (since declared by #class).
Make sure, that your code can see a declaration of WebFrame.
If so, maybe you add it later and XCode works with older meta data. In this case, a clean before build usually helps.
I am having an issue with ARC. It is not retaining the webview. The scenario is I have to send a webview from one viewcontroller to another one. The reason is when the user searches for something I want to take him to a new screen with some other options. (I have to use the same webview)
Here is the sample code: I have a ViewController1 which has a webview (I added it in the xib.) I am loading say google in it and once the user searches for something and when its done loading I have to take him to a new view controller and show the same webview in the new viewcontroller.
//ViewController1
#interface ViewController1 : UIViewController <UIWebViewDelegate>
#property (nonatomic, retain) UIWebView* testWebView;
#end
#implementation ViewController1
#synthesize testWebView;
- (void)viewDidLoad
{
[super viewDidLoad];
testWebView = [[UIWebView alloc]init];
testWebView.delegate = self;
[testWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:#"https://www.google.com"]]];
}
-(void)webViewDidFinishLoad:(UIWebView *)webView{
NSString *html = [testWebView stringByEvaluatingJavaScriptFromString:
#"document.body.innerHTML"];
if ([self.testWebView.request.url.absoluteString rangeOfString:#"output=search"].location != NSNotFound) {
ViewController2* newViewController = [[ViewController2 alloc] init];
[newViewController setTestWebView:self.testWebView];
[self.navigationController setViewControllers:[NSArray arrayWithObject:newViewController] animated:NO];
}
}
- (void)dealloc{
[self.testWebView stopLoading];
self.testWebView.delegate = nil;
self.testWebView = nil;
}
In the second view controller I am loading stackoverflow.com after a delay of 10 secs. The problem is it is loading stackoverflow fine, but it is not calling any of the delegate methods. Why?
#interface ViewController2 : UIViewController <UIWebViewDelegate>
#property (nonatomic, retain) UIWebView* testWebView;
#end
#implementation ViewController2
#synthesize testWebView;
- (void)viewDidLoad
{
[super viewDidLoad];
self.testWebView.delegate = self;
[self.view addSubview:testWebView];
[self performSelector:#selector(loadDifferentPage) withObject:nil afterDelay:10];
}
-(void)loadDifferentPage{
[self.testWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:#"http://www.stackoverflow.com/"]]];
}
-(void)webViewDidStartLoad:(UIWebView *)webView{
NSLog(#"%s", __PRETTY_FUNCTION__);
}
-(void)webViewDidFinishLoad:(UIWebView *)webView{
NSLog(#"%s", __PRETTY_FUNCTION__);
}
-(BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{
NSLog(#"%s", __PRETTY_FUNCTION__);
return YES;
}
ViewController2 is retaining the webview but the delegate methods are not being called. Why?
Thanks
Sai
ViewController1 delloc method was causing the issue:
If I uncomment out self.textWebView.delegate = nil it works fine. The reason is first we are setting the webview for newViewController and later in dealloc of ViewController1 we are setting its delegate to nil.
- (void)dealloc{
[self.testWebView stopLoading];
if(self.testWebView.delegate == self)
self.testWebView.delegate = nil;
self.testWebView = nil;
}
First thing I noticed is you're not specifying the instance variable name when synthesizing a property. That's just asking for collisions. Here's an example of how that should look:
#interface ViewController1 : UIViewController <UIWebViewDelegate>
#property (nonatomic, strong) IBOutlet UIWebView* testWebView;
#end
#implementation ViewController1
#synthesize testWebView=_testWebView;
Also, I noticed in ViewController1 you used IBOutlet so everything is probably wired up in Interface Builder. Try making sure that you set the delegate property in Interface Bulider because you don't set it in the implementation. That would be why you're not receiving any messages.
ViewController2 looks like you set the delegate in code. The problem is, you DON'T have IBOutlet in front of the property. Normally this would mean that you simply setup the WebView in code, but in your example you do not ever create a new instance of a UIWebView control and assign it to self.testWebView. This means that if it does display on the page, it's because Interface Builder was used to create it. You couldn't set the delegate in code without using IBOutlet in front of the testWebView declaration so that's probably why it's not working in exmaple two.
#interface ViewController2 : UIViewController <UIWebViewDelegate>
#property (nonatomic, strong) UIWebView* testWebView; // Mising IBOutlet
#end
#implementation ViewController2
#synthesize testWebView;
- (void)viewDidLoad
{
[super viewDidLoad];
// missing any code that would create the webview [[UIWebView alloc] init]
self.testWebView.delegate = self; // You set the delegate in code here
[self.view addSubview:testWebView];
[self performSelector:#selector(loadDifferentPage) withObject:nil afterDelay:10];
}
Hope this helps, I'd have to see your full implementation to get more specific than this.
Ok, so I'm a relative noob with Objective-C/iOS programming, so hopefully someone with more knowledge here can help me out.
I have an iPad application using the SplitViewController template (with Core Data). I created another UIViewController (with xib file) called PlayerViewController. This View has several UILabel components on it.
I have a list of players that show up in the RootViewController (UITableView) and when you select a player, I programmatically create a PlayerViewController (in DetailViewController), pass it the NSManagedObject that was passed to the DetailViewController, try to set the text of one of the labels on the PlayerViewController's view, and then add it as a subview to the DetailViewController.
All of this works great except for the setting the text of the label on the PlayerViewController's view. I'm not sure what I'm doing wrong. I have used NSLog to confirm that the NSManagedObject is not nil and that the NSManagedObject property I'm trying to use has the correct text.
I'm at a loss here. Any help would be greatly appreciated. (Code follows):
This method is in the DetailViewController.m file:
- (void)configureView {
// Update the user interface for the detail item.
PlayerViewController *player = [[PlayerViewController alloc] init];
player.player = detailItem;
[self.view addSubview:player.view];
}
This method is called when the user selects an item from the RootViewController (This functionality, calling of configureView, is setup by the template and I haven't changed it).
Setting the player property of the PlayerViewController to object detailItem is handled in the setPlayer method of that class.
- (void)setPlayer:(NSManagedObject *)managedObject {
if (player != managedObject) {
[player release];
player = [managedObject retain];
// Update the view.
[self configureView];
}
}
I then have a configureView method as well in PlayerViewController that sets the text of the label:
- (void)configureView {
nickName.text = [[player valueForKey:#"Nickname"] description];
NSLog(#"Nickname %#", [[player valueForKey:#"Nickname"] description]);
NSLog(#"Nickname %#", nickName.text);
}
Ok, so the first NSLog statement prints the desired value, but the text of the UILabel (called nickName) returns nil.
The following is the full PlayerViewController.h & .m files:
PlayerViewController.h:
#import <UIKit/UIKit.h>
#import <CoreData/CoreData.h>
#interface PlayerViewController : UIViewController {
NSManagedObject *player;
IBOutlet UILabel *nickName;
IBOutlet UILabel *goalCount;
IBOutlet UILabel *assistCount;
IBOutlet UILabel *timeInGame;
}
#property (nonatomic, retain) IBOutlet UILabel *nickName;
#property (nonatomic, retain) IBOutlet UILabel *goalCount;
#property (nonatomic, retain) IBOutlet UILabel *assistCount;
#property (nonatomic, retain) IBOutlet UILabel *timeInGame;
#property (nonatomic, retain) NSManagedObject *player;
#end
PlayerViewController.m:
#import "PlayerViewController.h"
#implementation PlayerViewController
#synthesize nickName, goalCount, assistCount, timeInGame, player;
#pragma mark -
#pragma mark Managing the detail item
/*
When setting the player item, update the view
*/
- (void)setPlayer:(NSManagedObject *)managedObject {
if (player != managedObject) {
[player release];
player = [managedObject retain];
// Update the view.
[self configureView];
}
}
- (void)configureView {
nickName.text = [[player valueForKey:#"Nickname"] description];
NSLog(#"Nickname %#", [[player valueForKey:#"Nickname"] description]);
NSLog(#"Nickname %#", nickName.text);
}
/*
// The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {
// Custom initialization
}
return self;
}
*/
/*
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
}
*/
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Overriden to allow any orientation.
return YES;
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (void)dealloc {
[super dealloc];
}
#end
I'm sure I'm just missing something trivial, but I can't figure it out, and haven't been able to find any answers searching the web.
Thanks for any help!
Ok, so after playing with this for a bit and searching and searching around, I have gotten the answer to my problem. It turns out all the code I had was fine except the location of one statement. My call to configureView in PlayerViewController.m needed to be in viewDidLoad() not in the setPlayer() method. It all works great now.
Change the configureView method to that :
- (void)configureView {
nickName.text = (NSString*)[player valueForKey:#"Nickname"];
}
Yes, better place to call method is
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[self configureView];
}
(void)setPlayer:(NSManagedObject *)managedObject called before your nib files loaded.