I use NSData object to maintain memory data. But when I use NSData.bytes to access the memory data. It will cause memory leak.
The sample code is as following:
char buf[12];
#interface ViewController ()
#property (nonatomic, copy) NSData *tempData;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.tempData = [[NSData alloc] initWithBytes:buf length:12];
[self loopReadData];
}
- (void)loopReadData {
while(true) {
[self calcData:self.tempData];
}
}
- (void)calcData:(NSData *) data {
const void *dataPtr = data.bytes; ///< memory leak
sleep(0.1);
}
#end
The sample code is very simple.But will cause memory leak and crash my app when no memory exits.
If I add autoreleasepool to the code. There is no memory leak again.
- (void)loopReadData {
while(true) {
#autoreleasepool {
[self calcData:self.tempData];
}
}
}
Related
I create a designer initializer with incoming arguments NSString *
In my class, i have property NSString* title.
#property (nonatomic) NSString *title;
...
- (instancetype)initWithTitle:(NSString*)title albumCover:(UIImage *)img {
self = [super init];
if (self) {
self.title = [[NSString alloc] initWithFormat:#"%#",title];
self.img = img;
}
return self;
}
with variable self.img everything good, but with self.title I have problems. If I want to log self.title I get error: Execution was interrupted, reason: EXC_BAD_ACCESS (code=2, address=0x16fcbbff0).
The process has been returned to the state before expression evaluation.
I tried to init before assigning, tried to with NSMutableString. Always the same thing. What I'm doing wrong?
The assignment isn't your problem. The problem is elsewhere. While the property declaration and initialization do not follow the recommended pattern, they aren't going to cause a crash in the code you've shown.
The following runs fine, for example. You should declare your #property as copy and assign to the instance variable directly (doing so avoids any issues that might spring up if you later implement a custom setter with business logic that requires a fully initialized object).
#interface Fo:NSObject
#property (nonatomic) NSString *wrongWay;
#property (nonatomic, copy) NSString *rightWay;
#end
#implementation Fo
- (instancetype)initWithTitle:(NSString*)title
{
self = [super init];
if (self) {
self.wrongWay = [[NSString alloc] initWithFormat:#"%#",title];
_rightWay = [title copy];
}
return self;
}
#end
int main(int argc, const char * argv[]) {
#autoreleasepool {
Fo *f = [[Fo alloc] initWithTitle:#"Fo"];
NSLog(#"%# %# %#", f, f.wrongWay, f.rightWay);
}
return 0;
}
Have a question about blocks in objective-c.
For example I have a list of actions.
I'm initializing an array of blocks:
self.actions = #[
^() { [self showObject:self.object_1]; },
^() { [self showObject:self.object_2]; },
^() { [self showObject:self.object_3]; }
];
And calling them when some row is pressed:
- (void)pressedRowAtIndex:(NSInteger)index {
if (index < actions.count) {
void (^action)() = [actions objectAtIndex:index];
if (action != nil) {
action();
}
}
}
And all works fine without problem. But when I init my actions array by using initWithObjects method:
self.actions = [NSArray alloc] initWithObjects:
^() { [self showObject:self.object_1]; },
^() { [self showObject:self.object_2]; },
^() { [self showObject:self.object_3]; },
nil
];
Than I get crash trying to get action by index by using objectAtIndex method of NSArray class.
I understand the difference between this inits. First one don't increase reference count like first do. But can someone explain why it crash?
Edit:
All that I've found. Maybe I'm nub and somewhere else is another useful information.
There is no crash info in terminal:
Code for Onik IV:
Small example:
#interface ViewController () {
NSArray *actions;
}
#property (nonatomic, strong) NSString *object1;
#property (nonatomic, strong) NSString *object2;
#property (nonatomic, strong) NSString *object3;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
actions = [[NSArray alloc] initWithObjects:
^() { [self showObject:self.object1];},
^() { [self showObject:self.object2]; },
^() {[self showObject:self.object3]; },
nil];
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
self.object1 = #"object 1";
self.object2 = #"object 2";
self.object3 = #"object 3";
void(^firsSimpleBlock)(void) = [actions lastObject];
firsSimpleBlock();
void(^simpleBlock)(void) = [actions firstObject];
simpleBlock();
}
-(void)showObject:(NSString *)object
{
NSLog(#"Show: %#",object);
}
#end
Try something like this.
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
(^someBlock)(void) = ^void(void){
self.object1;
};
actions = [[NSArray alloc] initWithObjects:
[someBlock copy],
[someOtherBlock copy],
[anotherBlock copy],
nil];
}
Blocks are allocated on the stack and are therefor removed when the frame is removed from the stack leading to sail pointers for all pointers pointing to that block. When you allocate a object with the literal "#" sign the object is allocated in a pool so all literals that are the "same" point to the same instance and are never deallocated.
NSString *a = #"A";
NSString *b = #"A";
points to the same instance of a string, while:
NSString *a = [NSString stringWithFormat:#"A"];
NSString *b = [NSString stringWithFormat:#"A"];
are two different objects.
So it works when you are creating a literal array but when you add the blocks dynamically they will be removed when its time to use them therefor the BAD_ACCESS. Solution is to send "copy" message to the block that will copy it to the heap and the block will not be released.
It´s the same, you must have another kind of problem (sintax?).
Try this:
#interface ViewController ()
#property (nonatomic, strong) NSString *object1;
#property (nonatomic, strong) NSString *object2;
#property (nonatomic, strong) NSString *object3;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.object1 = #"object 1";
self.object2 = #"object 2";
self.object3 = #"object 3";
NSArray *actions = #[^() { [self showObject:self.object1];},
^() { [self showObject:self.object2]; },
^() {[self showObject:self.object3]; }
];
NSArray *secondActions = [[NSArray alloc] initWithObjects:
^() { [self showObject:self.object1];},
^() { [self showObject:self.object2]; },
^() { [self showObject:self.object3];},
nil
];
void(^firsSimpleBlock)(void) = [actions lastObject];
firsSimpleBlock();
void(^simpleBlock)(void) = [secondActions firstObject];
simpleBlock();
}
-(void)showObject:(NSString *)object
{
NSLog(#"Show: %#",object);
}
#end
I have class for playing sound in app.
I implemented on/off switch(on GUI), for disabling and enablining sound play.
I am using BOOL property for that and this is working.
Now I am trying to implement saving that BOOL (is sound on/off) in file so that next time when app is started state is automatically restored.
For that I am using NSCoding protocol, archiving is working but I have problem with unarchiving.
My app will not start it will just show black screen.
This is my code, only part that I think it is important.
GTN_Sound.h
#import <Foundation/Foundation.h>
#import <AudioToolbox/AudioToolbox.h> // for playing sound
#interface GTN_Sound : NSObject <NSCoding>
#property(nonatomic, readwrite, unsafe_unretained) BOOL isSoundOn;
+ (id)sharedManager;
- (void)playWinSound;
- (void)playLoseSound;
#end
GTN_Sound.m
#pragma mark - NSCoding Methods
- (void)encodeWithCoder:(NSCoder *)aCoder
{
[aCoder encodeBool:self.isSoundOn forKey:#"isSoundOn"];
}
- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
self = [GTN_Sound sharedManager];
if (self) {
_isSoundOn = [aDecoder decodeBoolForKey:#"isSoundOn"];
}
return self;
}
I think that code is so far so good ?
Continuation of GTN_Sound.m
#pragma mark - itemArchivePath Method
- (NSString *)itemArchivePath
{
// Make sure that the first argument is NSDocumentDirectory
// and not NSDocumentationDirectory
NSArray *documentDirectories =
NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
// Get the one document directory from that list
NSString *documentDirectory = [documentDirectories firstObject];
return [documentDirectory stringByAppendingPathComponent:#"sound.archive"];
}
#pragma mark - custom seter Method
- (void)setIsSoundOn:(BOOL)theBoolean {
NSLog(#"My custom setter\n");
if(_isSoundOn != theBoolean){
_isSoundOn = theBoolean;
NSString *path = [self itemArchivePath];
[NSKeyedArchiver archiveRootObject:self toFile:path]; // this is doing save
}
}
It is done that for every time when switch on GUI is changed I do the savings.
This look fine from my side, because I am not expecting that user will change this many times.
Now the unarchiving comes and I thin that here are some problems.
#pragma mark - Singleton Methods
+ (id)sharedManager {
static GTN_Sound *sharedMyManager = nil;
// to be thread safe
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedMyManager = [[self alloc] initPrivate];
});
return sharedMyManager;
}
- (instancetype)init
{
#throw [NSException exceptionWithName:#"Singleton"
reason:#"Use +[GTN_Sound sharedManager]"
userInfo:nil];
return nil;
}
// Here is the real (secret) initializer
- (instancetype)initPrivate
{
self = [super init];
if (self) {
NSString *path = [self itemArchivePath]; // do as iVar, for futture
self = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
//_isSoundOn = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
}
return self;
}
I think that problem is in this line
self = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
But have no idea how to fix it.
I have read that when I am doing archiving, that I need to archive all properties of object.
Does this apply to private ivars also ?
Any help is appreciated.
Thanks
You can only archive NSObject inheriting objects. ie. NSNumber
[NSKeyedArchiver archiveRootObject:#YES toFile:path]; //to save
_isSoundOn = [[NSKeyedUnarchiver unarchiveObjectWithFile:path] boolValue]; //to load
Ok, I've been over this a million times in the last week and I just am not getting it. (And yes, I've read Apple's docs.)
I am archiving my object and it appears to be archiving correctly (I can see the file written to the file system and if I examine it I can see my data within). However, when I relaunch my app my data is not being restored. Every example I read tells me how easy this is but I'm just not getting it. One unique thing is that my object is a singleton, it's used for passing data between view controllers.
I'd really appreciate some sage advice. Thanks in advance.
Here's my header:
#import <Foundation/Foundation.h>
#interface SharedAppDataObject : NSObject <NSCoding>
{
NSMutableDictionary *apiKeyDictionary;
NSString *skuFieldText;
NSIndexPath *checkmarkIndex;
}
+ (SharedAppDataObject *)sharedStore;
#property (nonatomic, copy) NSString *skuFieldText;
#property (nonatomic, copy) NSIndexPath *checkmarkIndex;
#property (nonatomic, copy) NSMutableDictionary *apiKeyDictionary;
-(void)setValue:(NSString *)apiKey forKey:(NSString *)name;
-(void)setSkuField:(NSString *)s;
-(void)setCheckmarkIndex:(NSIndexPath *)p;
-(NSMutableDictionary *)apiKeyDictionary;
-(BOOL)saveChanges;
#end
Here's my implementation:
#import "SharedAppDataObject.h"
#implementation SharedAppDataObject
#synthesize skuFieldText;
#synthesize checkmarkIndex;
#synthesize apiKeyDictionary;
//create our shared singleton store
+(SharedAppDataObject *)sharedStore {
static SharedAppDataObject *sharedStore = nil;
if (!sharedStore) {
sharedStore = [NSKeyedUnarchiver unarchiveObjectWithFile:[SharedAppDataObject archivePath]];
if(!sharedStore)
sharedStore = [[super allocWithZone:NULL] init];
}
return sharedStore;
}
-(id) init {
self = [super init];
if (self) {
}
return self;
}
-(void)setValue:(id)apiKey forKey:(NSString *)name {
[apiKeyDictionary setObject:apiKey forKey:name];
}
-(void)setSkuField:(NSString *)s {
skuFieldText = s;
}
-(NSMutableDictionary *)apiKeyDictionary {
return apiKeyDictionary;
}
-(void)setCheckmarkIndex:(NSIndexPath *)p {
checkmarkIndex = p;
}
-(void)encodeWithCoder:(NSCoder *)aCoder {
[aCoder encodeObject:skuFieldText forKey:#"skuFieldText"];
[aCoder encodeObject:checkmarkIndex forKey:#"checkmarkIndex"];
[aCoder encodeObject:apiKeyDictionary forKey:#"apiKeyDictionary"];
}
-(id)initWithCoder:(NSCoder *)aDecoder {
self = [super init];
if (self) {
[self setSkuFieldText:[aDecoder decodeObjectForKey:#"skuFieldText"]];
[self setCheckmarkIndex:[aDecoder decodeObjectForKey:#"checkmarkIndex"]];
[self setApiKeyDictionary:[aDecoder decodeObjectForKey:#"apiKeyDictionary"]];
}
return self;
}
+(NSString *)archivePath {
NSArray *documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentDirectory = [documentDirectories objectAtIndex:0];
return [documentDirectory stringByAppendingPathComponent:#"bbyo.archive"];
}
-(BOOL)saveChanges {
return [NSKeyedArchiver archiveRootObject:self toFile:[SharedAppDataObject archivePath]];
}
#end
Save method from App Delegate:
- (void)applicationDidEnterBackground:(UIApplication *)application
{
BOOL success = [[SharedAppDataObject sharedStore] saveChanges];
if (success) {
NSLog(#"Saved all the data");
} else {
NSLog(#"Didn't save any of the data");
}
}
Initialize sharedStore = [NSKeyedUnarchiver unarchiveObjectWithFile:[SharedAppDataObject archivePath]]; in application:didFinishLaunchingWithOptions:. This method is used to initialize data structures and restore previous app state.
Also, take out static SharedAppDataObject *sharedStore = nil; from sharedStore. If the save file exists, [ShareAppDataObject sharedStore] will always unarchive the file which is not necessary. It can be unarchived once during initialization.
Here's a post that can answer your problem: http://bit.ly/PJO8fM
I cannot give you the answer but some ideas to figure this out. Taking this line:
sharedStore = [NSKeyedUnarchiver unarchiveObjectWithFile:[SharedAppDataObject archivePath]];
So if the sharedStore is nil, something is wrong - so test for it. If nothing then log the path, and use NSFileManager methods to see if the file is there, its size etc. If you find the file is there and has size, but you cannot unarchive it, that's a problem of course. In that case, add special debug code just after you create the file:
-(BOOL)saveChanges {
BOO ret = [NSKeyedArchiver archiveRootObject:self toFile:[SharedAppDataObject archivePath]];
id foo = [NSKeyedUnarchiver unarchiveObjectWithFile:[SharedAppDataObject archivePath]];
// check if foo is not nil, if its the proper class, etc.
}
If when you save the file you can unarchive it just fine, but cannot on restart of the app, then something is wrong with the file. All this info should point the way to a solution.
Another thought - when you encode the data, log it, just to be sure its not nil - but even if so the unarchive should work.
I'm running my app through Instruments, and every time the following setup causes a memory leak (apparently). I can't see an issue with this.
WeatherParser.h:
...
{
NSMutableDictionary *results;
}
#property (nonatomic, retain) NSMutableDictionary *results;
WeatherParser.m
- (void)parserDidStartDocument:(NSXMLParser *)parser
{
self.results = [[NSMutableDictionary alloc] init];
}
...add values to results
- (void)dealloc
{
self.results = nil;
[self.results release];
[super dealloc];
}
Would greatly appreciate any observations.
Swap these around to read:
[self.results release];
self.results = nil;
you were calling the release on the nil object not on the results array.