Removing last characters of NSString until it hits a separator - ios

Question

I've got a string that shows the stock amount using "-" as separators.
It's built up like this: localStock-wareHouseStock-supplierStock
Now I want to update the supplierStock at the end of the string, but as you can see in the code below it goes wrong when the original string returns more than a single-space value (such as 20).
Is there a way to remove all characters until the last "-" (or remove characters after the second "-")?
NSMutableString *string1 = [NSMutableString stringWithString: p1.colorStock];
NSLog(#"string1: %#",string1);
NSString *newString = [string1 substringToIndex:[string1 length]-2];
NSLog(#"newString: %#",newString);
NSString *colorStock = [NSString stringWithFormat:#"%#-%#",newString,p2.supplierStock];
NSLog(#"colorstock: %#",colorStock);
p1.colorStock = colorStock;
NSLog1
string1: 0-0-0
newString: 0-0
colorstock: 0-0-20
NSLog2
string1: 0-0-20
newString: 0-0-
colorstock: 0-0--20
EDIT: Got it working thanks to Srikar!
NSString *string1 = [NSString stringWithString: p1.colorStock];
NSLog(#"string1: %#",string1);
NSString *finalString = [string1 stringByReplacingOccurrencesOfString:[[string1 componentsSeparatedByString:#"-"] lastObject] withString:p2.supplierStock.stringValue];
NSLog(#"finalString: %#",finalString);
p1.colorStock = finalString;

Answer 1

Why not use componentsSeparatedByString followed by lastObject ?
NSString *supplierStock = [[string1 componentsSeparatedByString:#"-"] lastObject];
The above works if the "stock amount" is always in sets of 3's separated by a "-". Also since you always want supplierStock, lastObject is perfect for your needs.
Of course after splitting string1 with - you get a NSArray instance and you can access the individual components using objectAtIndex:index. So if you want localStock you can get by
NSString *localStock = [[string1 componentsSeparatedByString:#"-"] objectAtIndex:0];

Answer 2

I would suggest splitting the string into the 3 parts using [NSString componentsSeparatedByString:#"-"] and then building it back up again:
NSArray *components = [p1.colorStock componentsSeparatedByString:#"-"];
p1.colorStock = [NSString stringWithFormat:#"%#-%#-%#",
[components objectAtIndex:0],
[components objectAtIndex:1],
p2.supplierStock];

Answer 3

With a string that looks like
NSString *myString = #"Hello-World";
you can separate it with the componentsSeparatedByString: method of the NSString object as
NSArray *myWords = [myString componentsSeparatedByString:#"-"];
The myWords - array will then contain the two NSString objects Hello and World.
To access the strings:
NSString *theHelloString = [myWords objectAtIndex:0];
NSString *theWorldString = [myWords objectAtIndex:1];
Hope it helps!

Answer 4

None of these examples show how to do this if you are unaware of how many of these separator occurrences you're going to have in the original string.
Here's what I believe the correct the correct code should be for dismantling the original string and rebuilding it until you reach the final separator, regardless of how many separators it contains.
NSString *seperator = #" ";
NSString *everythingBeforeLastSeperator;
NSArray *stringComponents = [originalString componentsSeparatedByString:seperator];
if (stringComponents.count!=0) {
everythingBeforeLastSeperator = [stringComponents objectAtIndex:0];
for (int a = 1 ; a < (stringComponents.count - 1) ; a++) {
everythingBeforeLastSeperator = [NSString stringWithFormat:#"%#%#%#", everythingBeforeLastSeperator, seperator, [stringComponents objectAtIndex:a]];
}
}
return everythingBeforeLastSeperator;