I get an error (ARC forbids explicit message send of 'dealloc'), if I write:
- (void)dealloc {
self.slider = nil;
self.tabBar = nil;
[super dealloc];
}
Hope anyone can help me.
Thanks a lot for answering.
Remove [super dealloc], it's automatic under ARC.
Should be just:
- (void)dealloc
{
self.slider = nil;
self.tabBar = nil;
}
Related
I have the following methods in my SQLiteManager.m implementation. Warning: old legacy code alert
- (void)dealloc {
[super dealloc];
if (db != nil) {
[self closeDatabase];
}
[databaseName release];
}
- (NSError *) closeDatabase
{
NSError *error = nil;
if (db != nil) {
// Set and log error somewhere, not relevant here
}
db = nil;
}
return error;
}
When I run my app in debug mode on iOS 10 iPad, it runs fine. When I run my app in release mode on iOS 10 iPad (with development certificate and provisioning profile), the app crashes on the line [self closeDatabase];, returning a EXC_BAD_ACCESS. I see in my console that self still is an SQLiteManager object. How is it possible that a reference to a method in your own class can give rise to a bad access error, and only in release mode?
PS: When I run with NSZombieEnabled = YES, the app runs fine.
I found my answer. I had to place the call [super dealloc]; to the end of the overridden dealloc method.
- (void)dealloc
{
if (db != nil) {
[self closeDatabase];
}
[databaseName release];
[super dealloc];
}
So here's my problem: I've created a custom AVCaptureSession that takes pictures. I'm not sure why, but the third time you call startRunning, it crashes. I implemented didReceiveMemoryWarning, and it wasn't called before it crashed. I also ran instruments on it and there were no memory leaks associated with the AVCaptureSession. There were also no logs via console in XCode.
So my question is... is it a memory problem even though the didReceiveMemoryWarning wasn't called? Here's some of my code.
viewWillDisappear (ViewController)
- (void)viewWillDisappear:(BOOL)animated {
if (cameraFlashButton) { [cameraFlashButton release]; }
if (switchCamera) { [switchCamera release]; }
if (cameraBadgeBack) { [cameraBadgeBack release]; }
if (cameraBadgeNumber) { [cameraBadgeNumber release]; }
if (cameraUseButton) { [cameraUseButton release]; }
if (cameraOverlayView) { [cameraOverlayView release]; }
if (blackOverlay) { [blackOverlay release]; }
if (loadingIndicator) { [loadingIndicator release]; }
if (cameraPickButton) { [cameraPickButton release]; }
if (whiteOverlay) { [whiteOverlay release]; }
if (imageOverlay) { [imageOverlay release]; }
if (captureManager) { [captureManager release], captureManager = nil; }
if (theCaptureSession) { [theCaptureSession release], theCaptureSession = nil; }
[super viewWillDisappear:YES];
}
dealloc (CaptureSessionManager)
- (void)dealloc {
if ([self captureSession]) { [[self captureSession] stopRunning]; }
if (previewLayer) { [previewLayer release], previewLayer = nil; }
if (captureSession) { [captureSession release], captureSession = nil; }
if (stillImageOutput) { [stillImageOutput release], stillImageOutput = nil; }
if (stillImage) { [stillImage release], stillImage = nil; }
[super dealloc];
}
Ideas? If you need to see anything else, just ask! Thanks in advance.
If didReceiveMemoryWarning was properly implemented and it was never called, your problem is likely not due to running out of memory. There are many other ways you can get a crash when you start your capture session running. You'd need to post more of your implementation along with details of the crash to help debug this.
However, the code you posted has a number of inefficiencies and style problems. Note in Objective-C messages to nil are perfectly fine. So in your viewWillDisappear and dealloc methods you can and should remove every if test readability. For example, instead of:
if (cameraFlashButton) { [cameraFlashButton release]; }
just use:
[cameraFlashButton release];
If you are using properly synthesized accessors it is also much better to replace lines like
if (previewLayer) { [previewLayer release], previewLayer = nil; }
with simply
self.previewLayer = nil;
Updated post
Now, I have a EXC_BAD_ACCESS on the main 2 times out of 7 and I don't know why the heightOfPumpView result is 0 from the pumpCustomView class when the result of pumpViewHeight is 607.
PumpViewController.m
#import "PumpViewController.h"
#import "PumpModel.h"
#import "PumpCustomView.h"
#implementation PumpViewController
#synthesize labels;
#synthesize heightOfPumpView;
- (id)init
{
if (self = [super init])
{
labels = [[PumpModel alloc]init];
PumpCustomView* pumpView = [PumpCustomView alloc];
heightOfPumpView = [pumpView pumpViewHeight];
[labels pumpCreateLabel:heightOfPumpView];
labelsArray = [[NSMutableArray alloc]initWithArray:[labels labelsGroup]];
[labels release];
if (labelsArray!=nil)
{
[pumpView addSubview:[labelsArray objectAtIndex:2]];
}
[labelsArray release];
[pumpView release];
}
return self;
}
-(void) dealloc
{
[super dealloc];
}
#end
PumpModel.m
#import "PumpModel.h"
#import "PumpViewController.h"
#import "PumpCustomView.h"
#implementation PumpModel
#synthesize labelsGroup;
-(id)init
{
self = [super init];
return self;
}
-(void)pumpCreateLabel:(float)pumpViewHeight
{
theNumberOfPump = 8;
PumpViewController* pumpViewControllerAlloc = [PumpViewController alloc];
labelsGroup = [[NSMutableArray alloc]init];
for (int i = 0;i < theNumberOfPump; i++)
{
int pumpViewHeight = [pumpViewControllerAlloc heightOfPumpView];
int pumpViewWidthA = 259;
int resultHeight = pumpViewHeight/theNumberOfPump;
CGFloat resultWidth = pumpViewWidthA/2;
positionChart[i] = resultHeight * i;
newLabel[i] = [[NSTextField alloc] init] ;
[newLabel[i] setIntValue:i];
newLabel[i].frame = CGRectMake(resultWidth, positionChart[i], 300, 100);
newLabel[i].font= [NSFont fontWithName:#"Arial" size:12];
newLabel[i].textColor= [NSColor blackColor];
newLabel[i].backgroundColor= [NSColor whiteColor];
[labelsGroup addObject:newLabel[i]];
[newLabel[i] release];
NSLog(#"%# %d",[[labelsGroup objectAtIndex:i] stringValue],positionChart[i]);
}
[pumpViewControllerAlloc release];
}
-(void) dealloc
{
[labelsGroup release];
[super dealloc];
}
You shouldn't send messages to the object before [super init], e.g.:
- (id)init
{
if (self = [super init])
{
[self setNumberOfPump:8];
}
return self;
}
This is also true for:
-(id)initWithNumberOfPump:(int)numberOfPump
{
if (self = [super init]) {
theNumberOfPump = numberOfPump;
[self pumpCreateLabel];
}
return self ;
}
If you have a crash, post the backtrace of the crash.
Looking at your setNumberOfPump: method, it seems quite wrong.
labels is allocated, then released, likely leaving the instance variable as a dangling reference that'll crash later
labelsArray is leaked
your dealloc doesn't release any memory
You should try running Build and Analyze on your code, fixing any errors. The above issues combined with comments regarding the init patterns indicates that you should likely review the Objective-C documentation to gain a better understanding of both initialization and memory management patterns.
When my custom initializer fails, I am supposed to return nil. What is the convention for cleaning up any memory I've allocated in my initializer, that I was expecting would be cleaned up in dealloc?
Here is a contrived example:
- (id)init
{
if ((self = [super init])) {
instanceVar1 = [[NSString alloc] initWithString:#"blah"];
if (bad_thing_oh_noes) {
return nil;
}
}
return self;
}
- (void)dealloc
{
[instanceVar1 release];
[super dealloc];
}
A more realistic circumstance where I can't efficiently check every error condition before I do allocations would be deserializing a complex object containing arrays and the like.
Anyway, do I clean up the allocated memory before returning nil, do I send a dealloc message to self before returning nil, or is all of this managed for me magically?
If an error occurs during an initializer, you should call release on self and return nil.
if (bad_thing_oh_noes) {
[self release];
return nil;
}
Also, you must make sure that it is safe to call dealloc on a partially initialized object.
You should call release only at the point of failure. If you get nil back from the superclass’s initializer, you should not call release.
Normally, you should not throw an exception upon initialization failure.
An example from Handling Initialization Failure:
- (id)initWithURL:(NSURL *)aURL error:(NSError **)errorPtr {
self = [super init];
if (self) {
NSData *data = [[NSData alloc] initWithContentsOfURL:aURL
options:NSUncachedRead error:errorPtr];
if (data == nil) {
// In this case the error object is created in the NSData initializer
[self release];
return nil;
}
// implementation continues...
I am new to Objective-C and I am confused about this retain-release thing. Are parameters retained automatically? Do I need to release them?
Here is my code. Did I do the retain-release thing (and everything else) correctly?
#import "ACStringTokenizer.h"
#implementation ACStringTokenizer
- (id)init
{
self = [super init];
if (self) {
// Initialization code here.
}
return self;
}
- (id)initWithStr:(NSString *)theString
{
self = [super init];
if (self) {
string = [theString retain];
delimiters = #" ";
doesReturnDelims = NO;
}
return self;
}
- (id)initWithStr:(NSString *)theString andDelims:(NSString *)theDelimiters
{
self = [super init];
if (self) {
string = [theString retain];
delimiters = [theDelimiters retain];
doesReturnDelims = NO;
}
return self;
}
- (id)initWithStr:(NSString *)theString andDelims:(NSString *)theDelimiters andDoesReturnDelims:(BOOL)returnDelims
{
self = [super init];
if (self) {
string = [theString retain];
delimiters = [theDelimiters retain];
doesReturnDelims = returnDelims;
}
return self;
}
- (int)countTokens
{
return numberOfTokens;
}
- (BOOL)hasMoreTokens
{
return ![queue isEmpty];
}
- (NSString *)nextToken
{
return [queue remove];
}
- (void)dealloc
{
[string release];
[delimiters release];
[queue release];
[super dealloc];
}
#end
Thanks in advance.
P.S. How do I make init with no parameters invalid?
This might be better suited to http://codereview.stackexchange.com?
Anyway, a few points:
You should read up on the concept of Designated Initializer. In your case you'd probably make initWithStr:andDelims:andDoesReturnDelims: the designated initializer. Only this initializer may call [super init]. All other initializers call [self initWithStr:andDelims:andDoesReturnDelims:] instead of [super init].
There are some more elaborate ways to make init invalid, but if you want to disable it I'd simply make it return nil. However, I don't really see a reason why you'd want to do this in this particular case.
The retains in your init methods and the dealloc method seem to be alright. Method parameters are valid until the end of the method, if you want to keep them beyond that, e.g. in instance variables, you need to retain them (which you seem to have done correctly).
However, there's a whole lot of code omitted in your example so obviously I'm only commenting on what you've posted.
A parameter variable is not retained automatically, you only get the object by reference. To keep them you have to retain them, as you did. For me it looks perfectly fine what you did there.