Proper Memory Management for Objective-C Method
- by Justin
Hi, I'm programming an iPhone app and I had a question about memory management in one of my methods. I'm still a little new to managing memory manually, so I'm sorry if this question seems elementary.
Below is a method designed to allow a number pad to place buttons in a label based on their tag, this way I don't need to make a method for each button. The method works fine, I'm just wondering if I'm responsible for releasing any of the variables I make in the function.
The application crashes if I try to release any of the variables, so I'm a little confused about my responsibility regarding memory.
Here's the method:
FYI the variable firstValue is my label, it's the only variable not declared in the method.
-(IBAction)inputNumbersFromButtons:(id)sender {
UIButton *placeHolderButton = [[UIButton alloc] init];
placeHolderButton = sender;
NSString *placeHolderString = [[NSString alloc] init];
placeHolderString = [placeHolderString stringByAppendingString:firstValue.text];
NSString *addThisNumber = [[NSString alloc] init];
int i = placeHolderButton.tag;
addThisNumber = [NSString stringWithFormat:@"%i", i];
NSString *newLabelText = [[NSString alloc] init];
newLabelText = [placeHolderString stringByAppendingString:addThisNumber];
[firstValue setText:newLabelText];
//[placeHolderButton release];
//[placeHolderString release];
//[addThisNumber release];
//[newLabelText release];
}
The application works fine with those last four lines commented out, but it seems to me like I should be releasing these variables here. If I'm wrong about that I'd welcome a quick explanation about when it's necessary to release variables declared in functions and when it's not. Thanks.
