Substring to nth character - objective-c

Question

I need to substring to the 2nd comma in an NSString.
Input:
NSString *input = #"title, price, Camry, $19798, active";
Desired Output:
NSString *output = #"title, price";
Thanks!
UPDATE:
I have the following but the problem is it needs to skip the last comma:
NSString *output = [input rangeOfString:#"," options:NSBackwardsSearch];

Answer 1

Try this:
- (NSString *)substringOfString:(NSString *)base untilNthOccurrence:(NSInteger)n ofString:(NSString *)delim
{
NSScanner *scanner = [NSScanner scannerWithString:base];
NSInteger i;
for (i = 0; i < n; i++)
{
[scanner scanUpToString:delim intoString:NULL];
[scanner scanString:delim intoString:NULL];
}
return [base substringToIndex:scanner.scanLocation - delim.length];
}

Answer 2

this code should do what you need:
NSString *input = #"title, price, Camry, $19798, active";
NSArray *array = [input componentsSeparatedByString:#","];
NSArray *subArray = [array subarrayWithRange:NSMakeRange(0, 2)];
NSString *output = [subArray componentsJoinedByString:#","];
NSLog(output);

Answer 3

You could split -> splice -> join that string like this in objc:
NSString *input = #"title, price, Camry, $19798, active";
// split by ", "
NSArray *elements = [input componentsSeparatedByString: #", "];
// grab the subarray
NSArray *subelements = [elements subarrayWithRange: NSMakeRange(0, 2)];
// concat by ", " again
NSString *output = [subelements componentsJoinedByString:#", "];

Answer 4

You can try something like this:
NSArray *items = [list componentsSeparatedByString:#", "];
NSString result = #"";
result = [result stringByAppendingString:[items objectAtIndex:0]];
result = [result stringByAppendingString:#", "];
result = [result stringByAppendingString:[items objectAtIndex:1]];
You have to check you have at least two items if you want avoid an exception.

Answer 5

There's really nothing wrong with simply writing the code to do what you want. Eg:
int commaCount = 0;
int i;
for (i = 0; i < input.count; i++) {
if ([input characterAtIndex:i] == (unichar) ',') {
commaCount++;
if (commaCount == 2) break;
}
}
NSString output = nil;
if (commaCount == 2) {
output = [input substringToIndex:i];
}

Answer 6

You could create an NSString category to handle finding nth occurrences of any string. This is example is for ARC.
//NSString+MyExtension.h
#interface NSString(MyExtension)
-(NSString*)substringToNthOccurrence:(NSUInteger)nth
ofString:(NSString*)string;
-(NSString*)substringToNthOccurrence:(NSUInteger)nth
ofString:(NSString*)string
options:(NSStringCompareOptions)options;
#end
#implementation NSString(MyExtension)
-(NSString*)substringToNthOccurrence:(NSUInteger)nth
ofString:(NSString*)string
{
return [self substringToNthOccurrence:nth ofString:string options:0];
}
-(NSString*)substringToNthOccurrence:(NSUInteger)nth
ofString:(NSString*)string
options:(NSStringCompareOptions)options
{
NSUInteger location = 0,
strlength = [string length],
mylength = [self length];
NSRange range = NSMakeRange(location, mylength);
while(nth--)
{
location = [self rangeOfString:string
options:options
range:range].location;
if(location == NSNotFound || (location + strlength) > mylength)
{
return [self copy]; //nth occurrence not found
}
if(nth == 0) strlength = 0; //This prevents the last occurence from being included
range = NSMakeRange(location + strlength, mylength - strlength - location);
}
return [self substringToIndex:location];
}
#end
//main.m
#import "NSString+MyExtension.h"
int main(int argc, char *argv[])
{
#autoreleasepool {
NSString *output = [#"title, price, Camry, $19798, active" substringToNthOccurrence:2 ofString:#","];
NSLog(#"%#", output);
}
}
*I'll leave it as an exercise for someone to implement the mutable versions.