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?
Related
I eliminated all the leaks from my current app. However Instruments constantly tells me that I have a leak in the method shown below.
The leak is of type NSMutableArray and has a size of either 16 or 32 bytes. Yes, I know that's not much but it adds up. Also see it as an academic question that I need to solve to make my code leakless.
+ (id) meterFromDict:(NSDictionary*)dict {
Meter* resMeter = [[Meter alloc] initWithType:[[dict objectForKey:#"MeterBase"] intValue]];
//NSLog(#"dict: %#",dict);
resMeter.volume = nil;
resMeter.sounds = nil;
resMeter.repeats = nil;
resMeter.volume = [[[NSMutableArray alloc] initWithArray:[dict objectForKey:#"volumeArray"]] autorelease];
resMeter.sounds = [[[NSMutableArray alloc] initWithArray:[dict objectForKey:#"soundsArray"]] autorelease];
resMeter.repeats = [[[NSMutableArray alloc] initWithArray:[dict objectForKey:#"repeatsArray"]] autorelease];
//NSLog(#"MeterFromDict called and resmeter.repeats count is : %i",[resMeter.repeats count]);
resMeter.bpm = [[dict objectForKey:#"BPM"] floatValue];
return [resMeter autorelease];
}
Without looking at your Instruments output directly I can't tell exactly, but you're writing some redundant code: Try this:
+ (id) meterFromDict:(NSDictionary*)dict {
Meter* resMeter = [[Meter alloc] initWithType:[[dict objectForKey:#"MeterBase"] intValue]];
//NSLog(#"dict: %#",dict);
resMeter.volume = [dict objectForKey:#"volumeArray"];
resMeter.sounds = [dict objectForKey:#"soundsArray"];
resMeter.repeats = [dict objectForKey:#"repeatsArray"];
//NSLog(#"MeterFromDict called and resmeter.repeats count is : %i",[resMeter.repeats count]);
resMeter.bpm = [[dict objectForKey:#"BPM"] floatValue];
return [resMeter autorelease];
}
There's no point in nilling your properties before assigning new values to them.
Also, No point creating new arrays for arrays that you already have. And if you have properly declared your volume, sounds and repeats properties with copy instead of retain.
Try that and see if it works better.
In my
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
I am calculating the distance between 2 points, so i have
NSString *sDistance = [[NSString alloc] init];
if (curLat != 0) {
if (curLong != 0) {
double desLat = [[requestedDict objectForKey:#"latitude"] doubleValue];
double desLong = [[requestedDict objectForKey:#"longitude"] doubleValue];
double distance = sqrt(69.1*(desLat-curLat)*69.1*(desLat-curLat)+69.1*(desLong-curLong)*cos(curLat/57.3)*69.1*(desLong-curLong)*cos(curLat/57.3));
sDistance = [NSString stringWithFormat:#"(%.1f mi)",distance];
[[cell distanceLabel] setText:[NSString stringWithFormat:#"(%.1f mi)",distance]];
}
else{
sDistance = #"";
[[cell distanceLabel] setText:#""];
}
}
[sDistance release];
When i do this, i get exc_bad_access errors, but when i change it to
NSString *sDistance = [[[NSString alloc] init] autorelease];
It works just fine. Don't they do the same thing?
sDistance = [NSString stringWithFormat:#"(%.1f mi)",distance];
sDistance = #"";
In both lines sDistanceis pointing to a new string and so you are leaking the alloced string in the first line. When you send a autorelease message then it is added in autorelease pool and thus not leaked later. They are not same. When you alloc then you need to release that. Sending an autorelease message means the object is added to the autorelease pool and will be released later.
You do not need this alloc here as you are creating autoreleased strings later. Just declare the string in first line. And also remove the [sDistance release]; in last line.
NSString *sDistance; // alloc not required
Actually you are not using sDistance anywhere. It does not look like that you need this.
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.
I have the following method:
(void)makeString:(NSString *)str1,... {
va_list strings;
NSString *innerText = [[NSString alloc] init];
NSString *tmpStr = [[NSString alloc] init];
if (str1) {
va_start(strings, str1);
while (tmpStr = va_arg(strings, id)) {
innerText = [innerText stringByAppendingString:tmpStr];
}
label.text = [str1 stringByAppendingString:innerText];
}
[tmpStr release];
}
I will eventually get to Objective C Memory Management reading, where I'm sure I will find the answer to this - probably related to pointers and copying - , but for now, can anyone explain why if I add [innerText release]; as the last line of this function, i get an EXC_BAD_ACCESS error at runtime?
First, your code is erroneous.
As far as I can see you are only concatenating the strings to assign the result to label.text.
I assume that label is an ivar, so label.text = … ist legal. Then the following should do it:
- (void)makeString: (NSString *)str1, ...
{
if (str1) {
NSString *tmpStr;
va_list strings;
va_start(strings, str1);
while (tmpStr = va_arg(strings, id)) {
str1 = [str1 stringByAppendingString: tmpStr];
}
label.text = str1;
}
}
Some notes:
You should not release any input parameter unless your method is about releasing something.
As the first answer stated, you should not release the result of stringByAppendingString: unless
you have retained it before.
[Update]
I changed the answer because it contained an error. label.text = str1 should retain str1 of course (if it wants to keep it). Especially the calling code should not retain str1 unless it wants to keep it for itself.
stringByAppendingString returns an autoreleased string, which is replacing your original assignment. So your release is not needed. But you are leaking memory with the two allocs above.
You should probably use [NSString initWithCString:va_arg(strings, id)] to assign the tmpStr too.
I have a data source with about 2000 lines that look like the following:
6712,Anaktuvuk Pass Airport,Anaktuvuk Pass,United States,AKP,PAKP,68.1336,-151.743,2103,-9,A
What I am interested in is the 6th section of this string so I want to turn it into an array, then i want to check the 6th section [5] for an occurrance of that string "PAKP"
Code:
NSBundle *bundle = [NSBundle mainBundle];
NSString *airportsPath = [bundle pathForResource:#"airports" ofType:#"dat"];
NSData *data = [NSData dataWithContentsOfFile:airportsPath];
NSString *dataString = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];
NSArray *dataArray = [dataString componentsSeparatedByString:#"\n"];
NSRange locationOfAirport;
NSString *workingString = [[NSString alloc]initWithFormat:#""];
NSString *searchedAirport = [[NSString alloc]initWithFormat:#""];
NSString *airportData = [[NSString alloc]initWithFormat:#""];
int d;
for (d=0; d < [dataArray count]; d=d+1) {
workingString = [dataArray objectAtIndex:d];
testTextBox = workingString; //works correctly
NSArray *workingArray = [workingString componentsSeparatedByString:#","];
testTextBox2 = [workingArray objectAtIndex: 0]; //correctly displays the first section "6712"
testTextBox3 = [workingArray objectAtIndex:1] //throws exception index beyond bounds
locationOfAirport = [[workingArray objectAtIndex:5] rangeOfString:#"PAKP"];
}
the problem is that when the workingArray populates, it only populates with a single object (the first component of the string which is "6712". If i have it display the workingString, it correctly displays the entire string, but for some reason, it isn't correctly making the array using the commas.
i tried it without using the data file and it worked fine, so the problem comes from how I am importing the data.
ideas?
You code works. You should run it with the debugger to see what's happening. At a guess, your input data isn't what you think it is - possibly a different encoding, or different line endings.
See sample:
NSString *dataString = #"6712,Anaktuvuk Pass Airport,Anaktuvuk Pass,United States,AKP,PAKP,68.1336,-151.743,2103,-9,A";
NSArray *dataArray = [dataString componentsSeparatedByString:#"\n"];
for (NSString *workingString in dataArray) {
NSString *testTextBox = workingString; //works correctly
NSArray *workingArray = [workingString componentsSeparatedByString:#","];
NSString *testTextBox2 = [workingArray objectAtIndex: 0]; //correctly displays the first section "6712"
NSString *testTextBox3 = [workingArray objectAtIndex:1]; //throws exception index beyond bounds
NSRange locationOfAirport = [[workingArray objectAtIndex:5] rangeOfString:#"PAKP"];
}
there was a problem in the data where there were a few "\"s that caused the errors.