For a view in my iPhone application, I am using a subclass of the ABTableViewCell (https://github.com/enormego/ABTableViewCell). It's a fairly simple cell, but I wanted to use this for the scrolling speed I need, because a lot of them can in the table at once.
Here is the header of the file:
#interface WHUserTableViewCell : ABTableViewCell {
NSString* Name;
NSString* DetailsText;
UIImage* UserImage;
}
#property (nonatomic, copy) NSString* Name;
#property (nonatomic, copy) NSString* DetailsText;
#property (nonatomic, copy) UIImage* UserImage;
I know that by using 'copy' on an image, I am only supporting iOS 4.2 and up, but that is something I might fix later.
I follow the way AteBits uses this cell, by creating custom set methods for the properties, like this:
- (void) setUserImage:(UIImage *) userImage
{
[UserImage release];
UserImage = [userImage copy];
[self setNeedsDisplay];
}
- (void) setName:(NSString *) name
{
[Name release];
Name = [name copy];
[self setNeedsDisplay];
}
- (void) setDetailsText:(NSString *) detailsText
{
[DetailsText release];
DetailsText = [detailsText copy];
[self setNeedsDisplay];
}
The images that are assigned to the 'UserImage' property, are coming from a Singleton class, which provides caching and downloading of the images. So that class should be the 'owner' of the images.
There is only one problem, once the cell deallocs, and I release all the properties the application crashes on the [UserImage release] line, here's my dealloc method:
- (void)dealloc
{
[super dealloc];
[UserImage release];
[Name release];
[DetailsText release];
}
This cell uses custom drawing, just like AteBits explains in his famous blog post about this. What is the correct and fastest way to handle images for this. I would like to continue using my singleton caching/downloading class to handle images, but I don't think that is the source of the problem, since I am copying the image objects.
[super dealloc]; should be the last line of - (void)dealloc.
Related: Why do I have to call super -dealloc last, and not first?
Related
I just recently started learning Objective C/Cocoa and I know how important the memory management is and I believe this error I've been having is regarding to that.
I have a very very simple screen: two UITextView, one Button, one UILabel.
My header file has:
#interface PontaiViewController : UIViewController {
UITextField *loginField;
UITextField *passwordField;
UILabel *userID;
}
#property (nonatomic, retain) IBOutlet UITextField *loginField;
#property (nonatomic, retain) IBOutlet UITextField *passwordField;
#property (nonatomic, retain) IBOutlet UILabel *userID;
- (IBAction) btnLoginClicked:(id) sender;
The implementation has:
#implementation PontaiViewController
#synthesize loginField;
#synthesize passwordField;
#synthesize userID;
-(IBAction) btnLoginClicked:(id)sender {
NSString *string1 = #"username=";
NSString *string2 = [string1 stringByAppendingString:(loginField.text)];
NSString *string3 = [string2 stringByAppendingString:(#"&password=")];
NSString *post = [string3 stringByAppendingString:(passwordField.text)];
NSLog(#"The post is %#", post);
userID.text=loginField.text;
[string1 release];
[string2 release];
[string3 release];
[post release];
}
and it finishes with
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
self.loginField=nil;
self.passwordField=nil;
self.userID=nil;
}
- (void) dealloc {
[super dealloc];
[loginField release];
[passwordField release];
[userID release];
}
When I run this demo, and try to write something in the TextView, I get this error.
What could it be?
Regards,
Felipe
Also, your NSStrings are autoreleased, and then you're releasing them again (over releasing). Read up on memory management of convenience methods.
stringByAppendingString returns an autoreleased object, don't release string1, string2, string3 and post.
In viewDidUnload you set loginField to nil, then you try to release it in dealloc. This isn't right. You only need to release valid items that you own.
Additionally, (as pointed out in a comment) you need to put [super dealloc] at the end of the dealloc function.
As pointed out by others, you also should not release the strings you're getting from stringByAppendingString.
Here are some basic rules about how to manage memory in Objective-C under iOS:
https://developer.apple.com/library/ios/#documentation/general/conceptual/devpedia-cocoacore/MemoryManagement.html
One thing you will find is that you only release stuff you are responsible for, and you're not responsible for it unless it was created with one of these:
alloc, allocWithZone:, copy, copyWithZone:, mutableCopy, mutableCopyWithZone
You should comment out the following
//[string1 release];
//[string2 release];
//[string3 release];
//[post release];
since you are using helper methods and not explicitly allocating anything.
Edit:
Thanks #BlackFrog. I think I'm nearer now, but the values are still not get getting through...
The values are set as shown by logs within [progressController updateProgressSummary:...] but are nil when I log them in progressUpdate initWithProgressUpdate:.... as shown below.
I'm slightly confused over which property is used the one set for progressUpdate or the ones set for each of the 3 components of progressUpdate. I have changed the 3 individual properties from assign to retain as suggested and have also tried doing the same with the overall progressUpdate property too (not shown here).
progressController.h
......
#property (nonatomic, assign) ProgressUpdate *progressUpdate;
progressController.m
// Ask delegate to update and display Progress text
-(void) updateProgressSummary:(NSString *)summary detail:(NSString *)detail percentComplete:(NSNumber *)complete {
// These report the proper values
DLog(#"Reporting Summary - %s", [summary UTF8String]);
DLog(#"Reporting Detail - %s", [detail UTF8String]);
DLog(#"Reporting Complete - %i", [complete intValue]);
if (summary != nil)
self.progressUpdate.summaryText = summary;
self.progressUpdate.detailText = detail;
self.progressUpdate.percentComplete = complete;
ProgressUpdate *progressUpdateForIssue = [[ProgressUpdate alloc] initWithProgressUpdate:progressUpdate];
[self.delegate performSelectorOnMainThread:#selector(displayProgress:) withObject:progressUpdateForIssue waitUntilDone:NO];
[progressUpdateForIssue release];
}
But then a few milliseconds later...., inside the object....they're nil.
progressUpdate.h
.....
#property (nonatomic, retain) NSString *summaryText;
#property (nonatomic, retain) NSString *detailText;
#property (nonatomic, retain) NSNumber *percentComplete;
progressUpdate.m
-(id) initWithProgressUpdate:(ProgressUpdate *)update {
if ((self = [super init])) {
summaryText = [update.summaryText copy];
detailText = [update.detailText copy];
percentComplete = [[NSNumber alloc] initWithFloat:[update.percentComplete floatValue]];
}
// These report nil values
DLog(#"Reporting in progUpdate summaryText - %s", [summaryText UTF8String]);
DLog(#"Reporting in progUpdate detailText - %s", [detailText UTF8String]);
DLog(#"Reporting in progUpdate percentComplete - %i", [percentComplete intValue]);
return self;
}
end of update
I need some help with passing data in a custom class from one thread to another. Its there before the pass but then disappears upon arrival. I've tried everything I know, but to no avail.
My background thread calls ProgressController and passes it details of the current progress. That in turn does performSelectorOnMainThread on ProgressController's delegate (the view controller) to display the details.
It was all working fine when I was passing through a single NSString, but I need to pass two strings and a number and as performSelectorOnMainThread can only pass one object, I have encapsulated these in a custom object - ProgressUpdate.
The data gets through to ProgressController correctly but is null by the time that it appears in the View Controller. I know this as I've put NSLogs in various places.
I wonder if its to do with:
multithreading and custom objects
the fact that ProgressController is a singleton, which is why I have then alloc'd a new ProgressUpdate each time its called, but that has not helped.
Any ideas welcome. For clarity, the code is below.
ProgressUpdate.h
#import <Foundation/Foundation.h>
#interface ProgressUpdate : NSObject {
NSString *summaryText;
NSString *detailText;
NSNumber *percentComplete;
}
#property (nonatomic, assign) NSString *summaryText;
#property (nonatomic, assign) NSString *detailText;
#property (nonatomic, assign) NSNumber *percentComplete;
-(id) initWith:(ProgressUpdate *)update;
#end
ProgressUpdate.m
#import "ProgressUpdate.h"
#implementation ProgressUpdate
#synthesize summaryText, detailText, percentComplete;
-(id) initWith:(ProgressUpdate *)update {
self = [super init];
self.summaryText = update.summaryText;
self.detailText = update.detailText;
self.percentComplete = update.percentComplete;
return self;
}
#end
ProgressController.m
static ProgressController *sharedInstance;
+ (ProgressController *)sharedInstance {
#synchronized(self) {
if (!sharedInstance)
[[ProgressController alloc] init];
}
return sharedInstance;
}
+(id)alloc {
#synchronized(self) {
NSAssert(sharedInstance == nil, NSLocalizedString(#"Attempted to allocate a second instance of a singleton ProgressController.", #"Attempted to allocate a second instance of a singleton ProgressController."));
sharedInstance = [super alloc];
}
return sharedInstance;
}
-(id) init {
if (self = [super init]) {
[self open];
}
return self;
}
.........
// Ask delegate to update and display Progress text
-(void) updateProgressSummary:(NSString *)summary detail:(NSString *)detail percentComplete:(NSNumber *)complete {
if (summary != nil)
self.progressUpdate.summaryText = summary;
self.progressUpdate.detailText = detail;
self.progressUpdate.percentComplete = complete;
ProgressUpdate *progressUpdateForIssue = [[ProgressUpdate alloc] initWith:progressUpdate];
[self.delegate performSelectorOnMainThread:#selector(displayProgress:) withObject:progressUpdateForIssue waitUntilDone:NO];
[progressUpdateForIssue release];
}
RootViewController.m
// Delegate method to display specific text in Progress label
- (void) displayProgress:(ProgressUpdate *)update {
[progressSummaryLabel setText:update.summaryText];
[progressDetailLabel setText:update.detailText];
[progressBar setProgress:[update.percentComplete intValue]];
[progressView setNeedsDisplay];
}
In the init method, you are only assigning the ivars and not retaining them in the new object.
Redo your init method as the following:
-(id) initWithProgressUpdate:(ProgressUpdate *)update {
if ((self = [super init])) {
summaryText = [update.summaryText copy];
detailText = [update.detailText copy];
percentComplete = [[NSNumber alloc] initWithFloat:[update.percentComplete floatValue];
}
return self;
}
Couple of points:
You should not use accessor in the init method
Rename your init method to be a lot clear
In the #property, change the assign to retain
Try removing the statement '[progressUpdateForIssue release];' in the method
'-(void) updateProgressSummary:(NSString *)summary detail:(NSString *)detail percentComplete:(NSNumber *)complete '.
Also change the property attribute from 'assign' to 'retain' in your class ProgressUpdate.
You could release those properties in the dealloc method .
Good luck.
I am much confuse about my class.
Specially about Memory Management.
Please Guide me about NSString Concept at here.
My Class is.
#import <Foundation/Foundation.h>
#interface itinerary_detail : NSObject {
NSString *itinerary_title;
NSString *itinerary_creator;
NSString *itinerary_identifiere;
NSString *itinerary_created;
NSString *itinerary_modified;
}
#property (retain) NSString *itinerary_title;
#property (retain) NSString *itinerary_creator;
#property (retain) NSString *itinerary_identifiere;
#property (retain) NSString *itinerary_created;
#property (retain) NSString *itinerary_modified;
-(void) itinerary_initialization;
-(void) itinerary_title:(NSString *) xml_value;
-(void) itinerary_creator:(NSString *) xml_value;
-(void) itinerary_identifiere:(NSString *) xml_value;
-(void) itinerary_created:(NSString *) xml_value;
-(void) itinerary_modified:(NSString *) xml_value;
#end
and My .m class is
#import "itinerary_detail.h"
#implementation itinerary_detail
#synthesize itinerary_title,itinerary_creator,itinerary_identifiere,itinerary_created,itinerary_modified;
-(void) itinerary_initialization
{
itinerary_title=#"null";
itinerary_creator=#"null";
itinerary_identifiere=#"null";
itinerary_created=#"null";
itinerary_modified=#"null";
}
-(void) itinerary_title:(NSString *) xml_value
{
itinerary_title=xml_value;
}
-(void) itinerary_creator:(NSString *) xml_value
{
itinerary_creator=xml_value;
}
-(void) itinerary_identifiere:(NSString *) xml_value
{
itinerary_identifiere=xml_value;
}
-(void) itinerary_created:(NSString *) xml_value
{
itinerary_created=xml_value;
}
-(void) itinerary_modified:(NSString *) xml_value
{
itinerary_modified=xml_value;
}
-(void) dealloc
{
[itinerary_title release];
[itinerary_creator release];
[itinerary_identifiere release];
[itinerary_created release];
[itinerary_modified release];
[super dealloc];
}
#end
My question about.
1- Is this type Deceleration of NSString in this class of Memory Leak Issue. If Yes Please How i Will change this.
2- I am Using This class into Other class
Like that
itinerary_detail *check=[[itinerary_detail alloc] init];
[check itinerary_initialization];
[check release];
my question is this right way . or this is also a Memory Leak Issue.
Please Guide Me How to Deceleration Of this class and How to handle all memory Leak Issues.
Please Help Me
The problem come from the fact that you don't use the property but directly access the member variable. replace itinerary_title=xml_valueby self.itinerary_title=xml_value
btw, string properties are usually (copy) and not (retain) and why do you create all those methods while the synthesize will do it for you.
remove the methods from the .h file and from the .m file and set the property as
#property (copy) NSString* myString;
Your code shows that you need to get the basics of Cocoa and Objective-C right, before writing an actual program. Read Cocoa Fundamentals, OOP with Objective-C, etc. Resist the urge to start writing programs right now; the time you'll spend to learn the basics will greatly reduce your headache later.
Your code should look like:
#interface ItineraryDetail : NSObject {
NSString *itineraryTitle;
...
}
#property (retain) NSString *itineraryTitle;
#end
and
#implementation ItineraryDetail
#synthesize itineraryTitle, ... ;
-(id)init{
self=[super init];
if(self){
itineraryTitle=nil;
}
return self;
}
-(void) dealloc
{
[itineraryTitle release];
[super dealloc];
}
#end
and
ItineraryDetail *check=[[ItineraryDetail alloc] init];
... use it ...
[check release];
A few points:
In Objective-C, you don't usually name_like_this. You NameLikeThis. This is not an absolute rule, but it's customary, and you should follow it in general.
You don't write a method like ...Initialize separately. Rather, it's implemented using init, with [super init] inside it.
When you synthesize a property named foo via #synthesize foo, the setter setFoo: and the getter foo: are automatically generated, so you don't have to provide them manually. And you mistakenly used the name foo: for the setter! That will totally confuse the system.
The nil value for NSString (or any object in Objective-C in general) is not #"null" but just nil. And the ivars are set to nil automatically by the system, so you don't really do that in the initialization method.
I'm new to Objective-C and iPhone SDK development. I want to call a method in the same class:
- (void) setFilePath:(NSString *) p
{
[self methodCall];
}
- (void) methodCall
{
fileContent.text = #"Test"; //fileContent is a UITextView
}
If the property "filePath" is set, the method "setFilePath" is called. Then the UITextView, created in IB, should display the text. But that doesn't work ...
If I call the method directly via button in IB, then the UITextView changes his content successfully:
- (IBAction) clickButton
{
fileContent.text = #"Test";
}
What could be the problem?
Thanks for your answers!
EDIT 2: I solved the problem by setting "filePath" after pushing the view:
- (IBAction) showFileContent {
FileContentsViewController *fileContentsViewController = [[FileContentsViewController alloc] init];
[self.navigationController pushViewController:fileContentsViewController animated:YES];
fileContentsViewController.filePath = self.filePath;
fileContentsViewController.title = [NSString stringWithFormat:#"Content from von %#", [filePath lastPathComponent]];
[fileContentsViewController release];
}
EDIT 1: Here's the code of my interface:
#interface FileContentsViewController : UIViewController {
NSString *filePath;
UITextView *fileContent;
}
- (void) methodCall;
#property (nonatomic, retain) NSString *filePath;
#property (nonatomic, retain) IBOutlet UITextView *fileContent;
#end
... and here's the code of the implementation:
#import "FileContentsViewController.h"
#implementation FileContentsViewController
#synthesize filePath;
#synthesize fileContent;
- (void) setFilePath:(NSString *) p
{
NSLog(#"setFilePath executed!");
[self methodCall];
}
- (void) methodCall
{
fileContent.text = #"Test"; // UITextView
}
// some standard methods
#end
... and finally the code of the method that sets "filePath":
- (IBAction) showFileContent {
FileContentsViewController *fileContentsViewController = [[FileContentsViewController alloc] init];
fileContentsViewController.filePath = self.filePath;
fileContentsViewController.title = [NSString stringWithFormat:#"Content from von %#", [filePath lastPathComponent]];
[self.navigationController pushViewController:fileContentsViewController animated:YES];
[fileContentsViewController release];
}
What it looks like is that the fileContentsViewController created in -showFileContent doesn't have anything assigned to its FileContentsViewController.fileContent (or, at least, fileContent doesn't point to a UITextView that gets displayed) when fileContentsViewController.filePath is set.
You set filePath immediately after creating fileContentsViewController. If FileContentsViewController's -init doesn't create an appropriate fileContent, then when -setFilePath: is called from -showFileContent, there's no fileContent to set the text of. If fileContentsViewController is a typical view controller, fileContent won't exist until fileContentsViewController is loaded, which (I believe) happens during -pushViewController:animated.
One fix is to override -setFileContent to set fileContent.text as appropriate:
-(void)setFileContent:(UITextView*)fileContentView {
if (fileContent != fileContentView) {
[fileContent release];
fileContent = [fileContentView retain];
if (self.filePath) { // if file path is not nil
fileContent.text = ...;
}
}
}
Another other fix is to ensure you only set filePath when fileContent exists, but this is more brittle. A third is to set filePath after you push fileContentsViewController.
The way you would discover the cause during debugging is to check two things: execution ("Is the code I'm expecting to be executed ever reached?") and data ("Do the variables hold the values I expect?"). Set breakpoints in -showFileContent and -methodCall so you know that the methods are being called (which would be one reason for failure). If execution makes it into -methodCall, the problem must be something else. From there, examine the values of the variables used in -methodCall and you'll discover fileContent is either nil or not the same fileContent that shows up later.
Have you checked that fileContent has been set up at the time setFilePath is called? If you're trying to set things up at start up then it's possible that you're making calls before the views have been loaded (which the OS delays until the last possible moment).
You can force views to load by calling [self view] just before you try to access any of your Interface Builder views (NB don't call loadView - that doesn't do what you'd think).
If the problem is that setFilePath: is not called that I would guess that your code looks like
filePath = #"some value";
when it should be
self.filePath = #"some value";
When using #property you need to use self.filePath to call the methods, otherwise you will just access the ivar directly.
How have you define filePath property ?
I think that it is the problem...
I'm writing an iPhone app. I have a header file that looks like this:
#interface EditTagsViewController : UITableViewController {
NSMutableArray *allTags;
NSMutableArray *selectedTags;
NSInteger currentFavorite;
}
#property (nonatomic, retain) NSMutableArray *allTags;
#property (nonatomic, retain) NSMutableArray *selectedTags;
#property (nonatomic) NSInteger currentFavorite;
#end
In the implementation file, my viewDidLoad method looks like this:
- (void)viewDidLoad {
NSMutableArray *aTags = [[NSMutableArray alloc] initWithArray:[Tag findAllTags]];
self.allTags = aTags;
[aTags release];
NSMutableArray *sTags = [[NSMutableArray alloc] initWithArray:[Tag findByFavoriteId:currentFavorite]];
self.selectedTags = sTags;
[sTags release];
UIBarButtonItem *add = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:#selector(addNewTag:)];
self.navigationItem.rightBarButtonItem = add;
[add release];
[super viewDidLoad];
}
Here is my dealloc method:
- (void)dealloc {
[allTags release];
[selectedTags release];
[super dealloc];
}
What's confusing to me is that when I run the app both in the simulator and on the device itself, using Instruments (memory leaks), it tells me that this line in my viewDidLoad method is leaking an array:
self.selectedTags = sTags;
It's confusing because I'm using the exact same technique with 2 different variables, and yet no leak is reported with the first one.
I feel like I'm missing something obvious here. Any ideas?
Your code looks correct to me. Is it possible that one of [Tag findAllTags] or [Tag findByFavoriteId:] is leaking? Are you making sure to set self.allTags and self.selectedTags to nil in dealloc?
Be mindful of the difference between saying self.allTags = ... and allTags = .... Because allTags is a property and has the retain attribute, whenever you assign via self.allTags = ..., it implicitly calls the setter method [self setAllTags:...], which invokes retain on the new value and release on the old value (if any). You're doing it correctly in this code sample, but if elsewhere you're assigning straight to allTags (without the self.), you're not releaseing the old value, which may be the source of the leak. Likewise for selectedTags.
Have a look at findByFavoriteId is there a retain there? That is the only difference I can see between the aTags and sTags are used in your example