I'm getting a memory leak signal like the one shown in
how can i clear this, please help me .
Use (__bridge_transfer NSString *) instead of (__bridge NSString *)
With ARC, you can use __bridge_transfer to transfer memory management of the returned string to ARC
Example:
NSString *myString = [self encodeURL:#"hi*)"];
NSLog(#"%#",myString);
-(NSString *)encodeURL:(NSString *)string{
NSString *newString = #"";
newString = (__bridge_transfer NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (__bridge CFStringRef)string, NULL, CFSTR("^%*)*&%$"),CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding));
return newString;
}
Try this...
NSString *newString = nil;
CFStringRef stringRef = CFURLCreateStringByAddingPercentEscapes(...);
newString = (NSString *)stringRef;
CFRelease(stringRef);
if(newString)
return newString;
Use
return [newString autorelease];
The NSString object newString is got allocated in the function CFURLCreateStringByAddingPercentEscapes.
so the object attaining the retain count of one at this moment. So when you are retuning the retained object you got memory leak signal. We can add the object newString to the autorelease pool so that the os will take care of the memory to release at the right time.
Hope this helps.
Related
I am analyzing my application and face Potential leak of an object stored into setting username and setting password value my code is given
-(void) checkRememberPassword{
CFStringRef userNameKey = CFSTR("user_id_preferences");
CFStringRef settingUserName = (CFStringRef)CFPreferencesCopyAppValue(userNameKey, kCFPreferencesCurrentApplication);
CFStringRef passwordKey = CFSTR("password_preferences");
CFStringRef settingPasswordValue = (CFStringRef)CFPreferencesCopyAppValue(passwordKey, kCFPreferencesCurrentApplication);
NSString *tempString = (__bridge NSString *)settingPasswordValue;
NSString *tempString1 = (__bridge NSString *)settingUserName;
if(([tempString1 length] != 0) || ([tempString length] !=0)){
txtUserName.text = (__bridge NSString *)settingUserName;
txtPassword.text = (__bridge NSString *)settingPasswordValue;
[checkBoxButton setImage:[UIImage imageNamed:#"checkbox_full.png"] forState:UIControlStateNormal];
flagForRemPassword = YES;
}
}
The string returned by CFPreferencesCopyAppValue follows the Create rule (https://developer.apple.com/library/ios/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029) in Core Foundation -- you need to call CFRelease when you are finished with it. ARC does not do this for you.
Use CFBridgingRelease to transfer ownership of the object to ARC, instead of a simple C-style cast:
NSString *tempString = (NSString*)CFBridgingRelease(settingPasswordValue);
I have an iPhone application in which i am creating an array in the didfinishlaunch in the appdelegate. Like this:
for(int i=1;i<53;i++)
{
NSString *namestring=[NSString stringWithString:#"avatar"];
NSString *string = [NSString stringWithFormat:#"%d",i];
NSString *pngstring=[NSString stringWithString:#".png"];
string = [string stringByAppendingString:pngstring];
namestring = [namestring stringByAppendingString:string];
NSLog(#"%#",namestring);
[avtararray addObject:namestring];
}
working fine.and everywhere i am doing the avatar job with my avatararray in the appdelegate.But in one case when i pop back to the previous view and try to load the string from the array again
NSString *avatarstringt=[[appDelegate.avtararray objectAtIndex:i]description];here it is crashing with a an error
-[CFString description]: message sent to deallocated instance..
when doing the profile job i know that the leak is in the above loop in the appendingstring code.Can anybody help me to remove this?
First of all, Never do this
NSString *string = [NSString stringWithFormat:#"%d",i];
NSString *pngstring=[NSString stringWithString:#".png"];
string = [string stringByAppendingString:pngstring];
The following statements, are redundant
NSString *namestring=[NSString stringWithString:#"avatar"];
NSString *pngstring=[NSString stringWithString:#".png"];
and should be written as:
NSString *namestring=#"avatar";
NSString *pngstring=#".png";
You can use as :
NSString *namestring=#"avatar";
NSString *numberString = [NSString stringWithFormat:#"%d",i];
NSString *pngstring=#"png";
namestring = [namestring stringByAppendingFormat:#"%#.%#",numberString,pngstring];
Even the shortest of code :
for(NSInteger i=1;i<5;i++){
NSString *namestring = [NSString stringWithFormat:#"avatar%#.png",#(i)];
NSLog(#"%#",namestring);
}
As suggested by rmaddy: you can use i as integer, no need of converting it into nsnumber
NSString *namestring = [NSString stringWithFormat:#"avatar%d.png",i];
My app crashed when run to NSLog(#"...") statement, and the log on console showed an object was double freed. I used zombie instrument to check it, and got that one of strings in myAreas was over released. But I cannot understand why it happened? Any help? Thank you.
NSString *myArea = #"Europe";
NSArray *myTimeZones = [NSTimeZone knownTimeZoneNames];
NSMutableArray *myAreas = [NSMutableArray arrayWithCapacity:1];
[myTimeZones enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSString *name = (NSString *)obj;
if ([name hasPrefix:myArea]) {
NSString *tmpArea = [name substringFromIndex:myArea.length+1];
[myAreas addObject:tmpArea];
}
}];
NSLog(#"My Cities in %# time zone: %#", myArea, myAreas);
NSMutableArray is not thread safe, thus it can lead to subtle bugs when used in different threads, drop NSEnumerationConcurrent and it should work fine.
Im just wrapping up my app, so im onto the stage of running instruments to identify leaks in the app. Ive come across a leak that I cannot work out why it is being registered as a leak.
I have the following lines for example:
NSString *imageType = [[[NSString alloc] initWithString:[loopString substringToIndex:[loopString rangeOfString:#"</IMAGE>"].location]] autorelease];
imageType = [imageType substringFromIndex:[imageType rangeOfString:#"<IMAGE>"].location + :#"<IMAGE>".length];
So basically all im doing is pulling out a section of the "loopstring" and putting that into the imagetype string than just cutting off the trailing fluff of the string using the SubstringFromIndex method.
When I run instruments it says "NSCFString substringwithRange" leak. It highlights the second line:
imageType = [imageType substringFromIndex:[imageType rangeOfString:#"<IMAGE>"].location + :#"<IMAGE>".length];
I would think the substringFromIndex method should return a string that is automatically added to the autorelease pool.
Any ideas on where im going wrong?
Thanks
Following is the refactored code:
- (void)SetupTop10:(NSString *)Top10Data
{
while (Top10Data != #"") {
NSLog(Top10Data);
if ([Top10Data rangeOfString:#"</TOP10ENTRY>"].location == NSNotFound){
Top10Data = #"";
}
else
{
NSString *loopString = [Top10Data substringToIndex:[Top10Data rangeOfString:#"</TOP10ENTRY>"].location + 13];
Top10Data = [Top10Data stringByReplacingOccurrencesOfString:loopString withString:#""];
//NOW CREATE A RECORD FOR THIS ITEM
NSString *imageType = [loopString substringToIndex:[loopString rangeOfString:#"</IMAGE>"].location];
imageType = [imageType substringFromIndex:[imageType rangeOfString:#"<IMAGE>"].location + 7];
NSString *displayText = [loopString substringToIndex:[loopString rangeOfString:#"</DISPLAYTEXT>"].location];
displayText = [displayText substringFromIndex:[displayText rangeOfString:#"<DISPLAYTEXT>"].location + 13];
NSString *link = [loopString substringToIndex:[loopString rangeOfString:#"</INTERESTID>"].location];
link = [link substringFromIndex:[link rangeOfString:#"<INTERESTID>"].location + 12];
[Top10Images addObject:imageType];
[Top10Links addObject:link];
[Top10s addObject:displayText];
Top10RowCount = Top10RowCount + 1;
}
}
[self.Top10Table reloadData];
Top10Table.hidden = NO;
loadingLabel.hidden = YES;
loadingIndicator.hidden = YES;
}
//******************
It doesn't look leaky. But why
NSString *imageType = [[[NSString alloc] initWithString:
[loopString substringToIndex:[loopString
rangeOfString:#"</IMAGE>"].location]
] autorelease];
if you effectively get the same with
NSString *imageType = [loopString substringToIndex:[loopString
rangeOfString:#"</IMAGE>"].location];
with half the memory usage?
Leaks will tell you where the leaked memory was allocated. If you click around (there's a right-arrow icon by the memory address, I think) then you can look at all the allocations/retains/releases for that addresses.
In this example, Leaks will point you to the first line, when it's the fifth one that "leaks" (actually it's a missing release in dealloc/on assignment that leaks):
NSString * s = [someString substringFromIndex:1];
[myArray addObject:s];
// ...
NSString * s2 = [myArray lastObject];
instanceVariable = [s2 retain];
// ... and forget to release in dealloc
What does tableView:cellForRowAtIndexPath: do?
I can't see any problem in the above code. Did you release Top10Images in your dealloc method?
another memory management question:
I have asked this before, but did not really get an answer:
The question is would the following result in a leak or is it ok?
NSArray *txtArray = [NSArray array];
NSString *aTxtFieldTxt = [[NSString alloc]initWithString:aTxtField.text];
aTxtFieldTxt = [aTxtFieldTxt stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSMutableString *aTxt = [[NSMutableString alloc]initWithString:aTxtFieldTxt];
[aTxtFieldTxt release];
txtArray = [aTxt componentsSeparatedByString:#" "];
aTxt = [[txtArray objectAtIndex:0] retain];
for(int i = 1; i < [txtArray count]; i++){
[aTxt appendString:#"+"];
[aTxt appendString:[[txtArray objectAtIndex:i]retain]];
}
This is part of a function. And I am not sure if the assignment of aTxt = [[txtArray objectAtIndex:0] retain]; causes a leak because it is a pointer which originally points to
NSMutableString *aTxt = [[NSMutableString alloc]initWithString:aTxtFieldTxt];
[aTxtFieldTxt release];
How do I do this correctly. Would I have to use another pointer? Can somebody please explain this issue?
Thanks alot!
Lots and lots of issues with this code.
//
// Don't do this. Just declare the txtArray
//
NSArray *txtArray /* = [NSArray array]*/;
//
// You need to auto release after init in this case.
//
NSString *aTxtFieldTxt = [[[NSString alloc]initWithString:[aTxtField text]] autorelease];
//
// You are reassigning the aTxtFieldTxt and the new value is returned autoreleased.
//
aTxtFieldTxt = [aTxtFieldTxt stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
//
// Again, autorelease after init
//
NSMutableString *aTxt = [[[NSMutableString alloc]initWithString:aTxtFieldTxt] autorelease];
//
// You never alloced this instance so it needs no release.
//
/*[aTxtFieldTxt release]; */
//
// This array is returned autoreleased
//
txtArray = [aTxt componentsSeparatedByString:#" "];
//
// No need to retain here. Just get the object
//
aTxt = /*[*/[txtArray objectAtIndex:0]/* retain]*/;
for(int i = 1; i < [txtArray count]; i++)
{
[aTxt appendString:#"+"];
[aTxt appendString:[[txtArray objectAtIndex:i]retain]];
}
I have found, that if you have retains/releases outside of accessors/base int/dealloc routines, you are doing something wrong. For every alloc you must have a balanced release/retain for that instance of the object. If you reassign the variable, you will loose your reference to it.
This is a quick stab on how I would write this code:
NSArray *txtArray;
NSString *aTxtFieldTxt = [NSString stringWithString:[aTxtField text]];
NSMutableString *aTxt;
aTxtFieldTxt = [aTxtFieldTxt stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
aTxt = [NSMutableString stringWithString:aTxtFieldTxt];
txtArray = [aTxt componentsSeparatedByString:#" "];
aTxt = [NSMutableString stringWithString:[txtArray objectAtIndex:0]];
for(int i = 1; i < [txtArray count]; i++)
{
[aTxt appendString:#"+"];
[aTxt appendString:[[txtArray objectAtIndex:i]retain]];
}
Try running your application with Leaks. See if it causes a leak. Leaks is a tool in Instruments.
aTxtFieldTxt = [aTxtFieldTxt stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
This will cause the original reference to aTxtFieldTxt being lost (thus a leak). Even worse, a convenient function will return an object of retain count 0, so the -release later will crash the program.
It's better written as
// don't stuff everything into a single line.
NSCharacterSet* charsToTrim = [NSCharacterSet whitespaceAndNewlineCharacterSet];
// there's no need to create a copy of the string.
NSString* aTxtFieldTxt = [aTxtField.text stringByTrimmingCharactersInSet:charsToTrim];
// don't release stuff with retain count 0.
// you just want to replace all ' ' by '+' right? there's a method for that.
NSString* aTxt = [aTxtFieldTxt stringByReplacingOccurrencesOfString:#" "
withString:#"+"];
Edit: If you need to replace multiple spaces to one +, you need to parse the string, e.g.
NSCharacterSet* charsToTrim = [NSCharacterSet whitespaceAndNewlineCharacterSet];
NSString* aTxtFieldTxt = [aTxtField.text stringByTrimmingCharactersInSet:charsToTrim];
NSScanner* scanner = [NSScanner scannerWithString:aTxtFieldTxt];
[scanner setCharactersToBeSkipped:nil];
NSMutableString* aTxt = [NSMutableString string];
NSCharacterSet* whitespaceSet = [NSCharacterSet whitespaceCharacterSet];
while (![scanner isAtEnd]) {
NSString* res;
[scanner scanUpToCharactersFromSet:whitespaceSet intoString:&res];
[aTxt appendString:res];
if ([scanner scanCharactersFromSet:whitespaceSet intoString:NULL])
[aTxt appendString:#"+"];
}
As others pointed out, this code leaks all over the place.
A real good way to find those without even running your code is the static analyzer!
Use Build and Analyze from the Build menu, and it will show you what leaks and why, with complete code paths.