I am getting crazy during 4 hours and I really need help. Here is the code:
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
//check if strGroup has prefix and suffix #
BOOL result;
result = [strGroup hasPrefix: #"#"];
if (result)
{
result = [strGroup hasSuffix: #"#"];
if (result)
{
NSMutableString* string = [NSMutableString stringWithString: strGroup];
str = [strGroup substringWithRange: NSMakeRange (1, [string length]-2)];
strToHoldAllContact = [NSString stringWithFormat:#"%#",str];
}
}
NSLog(#"strToHoldAllContact=%#",strToHoldAllContact);
}
I am gettin the value of strToHoldAllContact correctly. But when I try to access strToHoldAllContact from another method I am getting the error:
[CFString respondsToSelector:]: message sent to deallocated instance 0x856f2a0
Use
strToHoldAllContact = [NSString stringWithFormat:#"%#",str];
[[strToHoldAllContact retain] autorelease];
and forget about release.
where ever you are initializing or setting the string do this [strToHoldAllContact retain]; and don't forget to release it once you are done using it
Just replace
strToHoldAllContact = [NSString stringWithFormat:#"%#",str];
to
strToHoldAllContact = [[NSString alloc] initWithFormat:#"%#",str];
And release it after you don't need it anymore.
with ARC, in .h declare strToHoldAllContact as:
#property(strong) NSString *strToHoldAllContact;
in .m, use it (after #synthesize) as self.strToHoldAllContact = [NSString stringWithFormat:#"%#",str];
this way you will not have problems.
without ARC,in .h declare strToHoldAllContact as:
#property(retain) NSString *strToHoldAllContact;
and use it same ways as with ARC in.m file.
Related
Assuming we don't use ARC.
Suppose we have a very simple class in which we declare 2 NSString properties, like this :
#interface Foo : UIView {}
-(id)initWithArguments:(NSString*)mess title:(NSString*)tit;
#property(nonatomic, retain) NSString *message;
#property(nonatomic, retain) NSString *title;
#end
and in implementation :
#implementation Foo
#synthesize message, title;
-(id)initWithArguments:(NSString*)mess title:(NSString*)tit{
if((self = [super init])){
message = mess; // (1)
self.title = tit; // (2)
(...)
}
return self;
}
-(void)dealloc{
message = nil;
title = nil;
[super dealloc];
}
#end
Now if I call a method from another class, in which I create 2 NSString and an instance of Foo , like this :
-(void)someMethod{
NSString *string1 = [NSString stringWithFormat:#"some text with %d things", 5];
NSString *string2 = [NSString stringWithFormat:#"other text with %d things", 5];
Foo *foo = [[Foo alloc] initWithArguments:string1 title:string2];
}
The whole code works fine and doesn't crash, but, if I profile it with instruments,
it doesn't cause a leak when calling (1)("message = mess;")
it cause a leak when calling (2)("self.title = tit;")
It's very confusing, because stringWithFormat is an autoreleased object, isn't it ?
So, how an autoreleased object can cause a leak when assigning to a property ???
I read somewhere that it's almost always better to use the "self.text = value;" form instead of the "text = value;" form, because the second one may cause a leak.
Actually, in this code it's the contrary.
And... If I use a constant NSString like #"some text", instead of the values returned by [NSString stringWithFormat], there is no leak, of course.
Any idea ?
You have forgotten to invoke the (compiler-generated) setter methods in a few cases:
self.message = mess; // in init method
self.message = nil; // in dealloc method
self.title = nil; // ditto
It's crucial that you use the setter/getter methods in non-ARC code.
A little background here before I get started, basically we are looking to compare a UDP response with a string stored in Parse's database for our app. This issue is that I can't seem to get the strings to be considered equal by the isEqualToString function. Here's the code I have running now, I have tried a few work-arounds I've seen in other questions but it still doesn't work.
- (BOOL) onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData *)data withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port
{
if(tag == TAG_SINGLE_GRILL)
{
NSString *grillId = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
if(grillId.length > 11)
{
grillId = [grillId substringToIndex:11];
}
grillId = [NSString stringWithFormat:#"%#", grillId];
if([grillId hasPrefix:#"GMG"])
{
for(int i = 0; i < [parseGrills count]; i++)
{
NSString *parseGrillId = [[parseGrills objectAtIndex:i] grillId];
parseGrillId = [NSString stringWithFormat:#"%#", parseGrillId];
//If we match the id, add it to found grills
if([grillId isEqualToString:parseGrillId])
{
//do stuff
}
}
}
NSLog(#"Grill ID : %#", grillId);
}
return TRUE;
}
parseGrills is an NSMutableArray with a very basic Grill object, I use synthesize for the properties, otherwise the .m file is essentially empty.
#import <Foundation/Foundation.h>
#interface Grill : NSObject
#property (nonatomic) NSString* grillId;
#property (nonatomic) NSString* ipAddress;
#end
Here's a screen shot of the debugger after it returns false
Any help would be greatly appreciated. Thanks.
I guess that they are of different encoding.
I have run this experiment and see that if the encoding is different, it will return NO. So, try converting parseGrillId to utf8 with the code below.
NSString *s1 = [NSString stringWithCString:"HELLO123" encoding:NSUTF8StringEncoding];
NSString *s2 = [NSString stringWithCString:"HELLO123" encoding:NSUTF16StringEncoding];
NSString *s3 = [NSString stringWithUTF8String:s2.UTF8String];
if ([s1 isEqualToString:s2]) {
NSLog(#"s1 == s2");
}
if ([s1 isEqualToString:s3]) {
NSLog(#"s1 == s3");
}
Will print s1 == s3.
I guess its a very basic memory concept. But couldn't figure it out what happens with below case. Any insight would be helpful.
This could be similar to Problems with NSString inside viewWillDisappear
But I wanted to know why there requires a #property. How can we do it without taking #property. Please provide some inside view.
in .h I have NSString *someString
in .mm (this is my non-ARC cocos2d+box2d game scene)
-(id)initWithString:(NSString *)tempString
{
if(self = [super init])
{
someString = [[NSString allo]init];
someString = tempString;
}
return self;
}
-(void)onEnterTransitionDidfinish
{
[super onEnterTransitionDidfinish];
NSLog("The String is %#",someString);//Becomes nil here
}
-(void)printString
{
NSLog(#"The String is %#",someString);//This works fine
}
If you are not using ARC then you need to learn a lot more about memory management.
The following two lines:
someString = [[NSString allo]init];
someString = tempString;
should be:
someString = [tempString copy]; // or [tempString retain];
And be sure you call [someString release] in your dealloc method.
BTW - you are not using a property. someString is declared as an instance variable, not a property.
For example,
- (void) method
{
NSString *string = #"This is a string.";
}
Do I need to add
string = nil;
at the end of the method in order to let ARC release it?
Situation may be different in non-literal object such as
- (void) method
{
NSData *data = [[NSData alloc] init];
}
Do I need to add at the end
data = nil;
to release it?
You don't need to nil it, but ARC doesn't release it either. Since it's a literal, it's statically allocated in the app's binary. It's never released.
- (void)method {
NSString *string = #"I'm never released because I'm statically allocated";
NSString *arcReleasesMeAfterMyLastSourceRef = [NSString stringWithString:string];
}
In my app, I have a view where user have to fill a form. But, sometime the app crash here, in this function, that simple cacth the value field and built a url to give
-(NSString*)urlToUpload{
NSString *string1 =[[NSString alloc]init];
string1= [NSString stringWithFormat:#"?nombre="];
NSString *string2 = [string1 stringByAppendingString:nameAdded];
//crash here
NSString *string3 = [string2 stringByAppendingString:#"&horario="];
NSString *string4 = [string3 stringByAppendingString:horarioAdded];
NSString *string5 = [string4 stringByAppendingString:#"&info="];
NSString *string6 = [string5 stringByAppendingString:infoAdded];
NSString *string7 = [string6 stringByAppendingString:#"&offerta="];
NSString *string8 = [string7 stringByAppendingString:offertaAdded];
NSString *lat_string = [[[NSString alloc] initWithFormat:#"%f",locationToUpload2.latitude] autorelease];
NSString *lon_string = [[[NSString alloc] initWithFormat:#"%f",locationToUpload2.longitude] autorelease];
NSString *string9 = [string8 stringByAppendingString:#"&latitude="];
NSString *string10 = [string9 stringByAppendingString:lat_string];
NSString *string11 = [string10 stringByAppendingString:#"&longitude="];
NSString *string12 = [string11 stringByAppendingString:lon_string];
NSString *url1 = [NSString stringWithFormat:#"http://myserverside/mysql_up.php"];
NSString *url = [url1 stringByAppendingString:string12];
return url;
}
EDIT:
It seems problem appers on nameAdded when there is a white space into textField(i.e. MisterB not crash, Mister B yes ).
But I am using:
nameAdded =[[nameField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
and NSLOg give of nameAdded is Mister%20B.
The crash still appearing...
Just use a single stringWithFormat::
- (NSString *)urlToUpload {
NSString *url = [NSString stringWithFormat:#"http://myserverside/mysql_up.php?nombre=%#&horario=%#&info=%#&offerta=%#&latitude=%f&longitude=%f",
[nameAdded stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding],
[horarioAdded stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding],
[infoAdded stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding],
[offertaAdded stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding],
locationToUpload2.latitude, locationToUpload2.longitude];
return url;
}
Make sure the referenced variables are valid.
In your original code there is no need to alloc/init an NSString then assign another string to the same variable. That's a memory leak (string1).
If you really want to structure your code the way you have it, at least use an NSMutableString and append to that one mutable string. Creating over a dozen NSString variables is the wrong way to do it.
Updated: Ensure each of the strings added to the URL are properly escaped.
It looks like nameAdded may be the cause of your problems. Is it nil at that point?
Also
You are allocating a string, setting it to string1 and then immediately setting string1 to the class function stringWithFormat which allocates another string. Also you are using stringWithFormat but you aren't using any format so you could simply use NSString *string1 = #"?nombre=";
Rather than declaring all of those variables you should just use NSMutableString and build it all in one variabl