NSScanner to scan until a character or number is Hit - ios

Question

My problem is that I want to extract the data from the string. The strings prints 1000 lines with some random data fetched from web. The string is like this:
Level
1
2
3
4
5
6
7
8
Score
0
0
0
0
0
0
0
0
I need NSScanner to save data in array like this
int *extractedLevelData = {1, 2, 3, 4, 5, 6, 7, 8}
int *extractedScoreData = {0, 0, 0, 0, 0, 0, 0, 0}
The problem is that the row of number in level and score is dynamic, it goes from 1 then new line then 2 then new line then 3 then new line and so on. The challenge is that sometimes it can be 1 to 5 or sometimes it can be 1 only and sometimes maximum is 1 to 8. They show up in the same style as shown above followed by new line character. Same with the "Score".
I've tried this but the saved data returns null in NSLog, it has been 7 days since I'm learning Objective C and I'm almost finished with the app until this problem came.
Here is what I've tried:
NSString *extractedData;
NSCharacterSet *tripleNewLine = [NSCharacterSet characterSetWithCharactersInString:#"\n\n\n"];
[firstScanner scanString:#"Level" intoString:NULL];
[firstScanner setScanLocation:[firstScanner scanLocation]];
[firstScanner scanUpToCharactersFromSet:tripleNewLine intoString:&extractedData];
NSLog(#"%#", extractedData);
Note that this is just a code snippet and the real problem is really complex but if someone smart enough to solve this problem then my problem will be solved! The logic can be: tell the NSScanner to scan from "Level" text with numbers until it hit any character.

Answer 1

So if you don't really want to use NSScanner another solution can be the following:
Split the whole string by Score this will give you two strings one with the values from score and one with the values from level:
`NSArray *components = [serverString componentsSeparatedByString:#"Score"];`
The above line will split your server string in two strings contained by components array. One will have all the values from Level including Level, and the other one will have the values from Score without Score value.
Now you can split those two strings by \n character, this will result in two arrays with all the values from a row.
if(components.count > 1) { //we better check if we have both substrings
NSArray *levels = [[components objectAtIndex:0] componentsSeparatedByString:#"\n"];
NSArray *scores = [[components objectAtIndex:1] componentsSeparatedByString:#"\n"];
}
Now after you have the all the values we should create a method that will check if a value is an actual number, if not we will remove it from the array.
-(NSArray *)checkAndRemoveNonNumbersFromArray:(NSArray *)checkedArray {
NSCharacterSet *alphaNums = [NSCharacterSet decimalDigitCharacterSet];
checkedArray = [checkedArray filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(NSString *evaluatedObject, NSDictionary *bindings) {
NSCharacterSet *inStringSet = [NSCharacterSet characterSetWithCharactersInString:evaluatedObject];
return [alphaNums isSupersetOfSet:inStringSet];
}]];
return checkedArray;
}
Now that we have the method created, the code from point 2 will become:
if(components.count > 1) { //we better check if we have both substrings
NSArray *levels = [[components objectAtIndex:0] componentsSeparatedByString:#"\n"];
NSArray *scores = [[components objectAtIndex:1] componentsSeparatedByString:#"\n"];
levels = [self checkAndRemoveNonNumbersFromArray:levels];
scores = [self checkAndRemoveNonNumbersFromArray:scores];
}
Now levels & scores will have only numerical values from those two arrays. Note, this is not the best solution, is more a solution to show you how you can play with strings, after you understand this implementation I think you can find one that uses NSScaner.

Answer 2

I see that you are passing #"Level" as a string input rather than a variable, which is not correct. I assume Level is the NSString object in this case. You can use this solution. This will print all the data from Level
NSScanner *scanner = [NSScanner scannerWithString:Level];
while([scanner isAtEnd] == NO) {
[scanner setScanLocation:[scanner scanLocation]];
[scanner scanUpToCharactersFromSet:tripleNewLine intoString:&extractedData];
NSLog(#"%#", extractedData);
}