Issue with NSString memory management - objective-c

Question

I have developed in C but am quite new to Objective-C and iPhone app development. I am working on an app that needs to strip the punctuation off a string. The function works but when I analyse the code it flags up some issues around one of the NSstrings I am using.
I don't understand why and therefore don't know how to fix it.
The code for the main function along with the analyser warning is:
- (IBAction)doIt {
NSString *start_punct = [[NSString alloc] init];
NSString *end_punct = [[NSString alloc] init];
NSString *actual_word = [[NSString alloc] init];
outputTextTextView.text = translatedText; //potential leak of an object alloctated on line xx and stored into 'actual word'
[translatedText release]; translatedText = nil;
[start_punct release]; start_punct = nil; //incorrect decrement of reference count of an object that is not owned at this point by the caller
[end_punct release]; end_punct = nil;
[actual_word release]; actual_word = nil; //this causes a crash
start_punct = [MainViewController getStartPunct:word start:&start_range_start len:&start_range_len];
end_punct = [MainViewController getEndPunct:word start:&end_range_start len:&end_range_len];
actual_word = [word substringWithRange: NSMakeRange(start_range_start,(end_range_start-start_range_start)+1)];
}
The code for the getStartPunct and getEndPunct functions is below
+(NSString*) getStartPunct:(NSString*) inputString
start:(NSInteger*)rangeStart
len:(NSInteger*)length {
NSString* start_str = nil;
NSRange firstAlphanumCharFromStart = [inputString rangeOfCharacterFromSet:[NSCharacterSet alphanumericCharacterSet]];
if (firstAlphanumCharFromStart.location != NSNotFound) {
start_str = [inputString substringWithRange: NSMakeRange(0, firstAlphanumCharFromStart.location)];
*length = firstAlphanumCharFromStart.length;
*rangeStart = firstAlphanumCharFromStart.location;
} //if
if (start_str == nil) {
*length=0;
*rangeStart=0;
}
return start_str;
} //getStartPunct
+(NSString*) getEndPunct:(NSString*) inputString
start:(NSInteger*)rangeStart
len:(NSInteger*)length {
NSString* end_str = nil;
NSInteger rnge = inputString.length;
NSCharacterSet* CS = [NSCharacterSet alphanumericCharacterSet];
NSRange firstNonAlphanumCharFromEnd = [inputString rangeOfCharacterFromSet:CS options:NSBackwardsSearch];
if (firstNonAlphanumCharFromEnd.location != NSNotFound) {
end_str = [inputString substringWithRange: NSMakeRange(firstNonAlphanumCharFromEnd.location+1, rnge - firstNonAlphanumCharFromEnd.location-1)];
*length = firstNonAlphanumCharFromEnd.length;
*rangeStart = firstNonAlphanumCharFromEnd.location;
} //if
if (end_str == nil) {
*length=0;
*rangeStart=0;
}
return end_str;
} //getEndPunct
Can someone see what the issue is? I'm sure it is something very basic..
Many Thanks in advance!
Thanks for all the responses so far.
adpalumbo you are right, I had paste the elements in the wrong order. The correct order is below and I have changed the initialization as suggested by Alex Nichol.
This has fixed 1 of the warning but the others (as shown below) still remain and I don't understand why 'start_punct' and 'end_punct' are behaving differently
- (IBAction)doIt {
NSString *start_punct = nil;
NSString *end_punct = nil;
NSString *actual_word = nil;
start_punct = [MainViewController getStartPunct:word start:&start_range_start len:&start_range_len]; // method returns objective with +0 retain count
end_punct = [MainViewController getEndPunct:word start:&end_range_start len:&end_range_len];
actual_word = [word substringWithRange: NSMakeRange(start_range_start,(end_range_start-start_range_start)+1)];
[translatedText release]; translatedText = nil;
[start_punct release]; start_punct = nil; //incorrect decrement of reference count
[end_punct release]; end_punct = nil;
//[actual_word release]; actual_word = nil; //possible abend
}