Dynamically append and remove substring from NSString - objective-c

Question

I am dynamically appending and removing substring from NSString -
At specific action I am appending using (I am using comma separator while adding a new string)-
self.selectedString = [self.selectedString length] < 1 ? newSelectedString
: [self.selectedString stringByAppendingFormat:#",%#",newSelectedString];
Removing -
Now this comma is creating problem for me when removing string.
Currently I am using a solution for this as -
self.selectedString = [self.selectedString stringByReplacingOccurrencesOfString:newSelectedString
withString:#""];
NSRange rangeSingleComma = [self.selectedString rangeOfString:#","];
NSRange rangeDoubleComma = [self.selectedString rangeOfString:#",,"];
if (rangeSingleComma.location == [self.selectedString length] - 1) {
self.selectedString = [self.selectedString substringToIndex:[self.selectedString length] - 1];
}
if (rangeSingleComma.location == 0) {
self.selectedString = [self.selectedString substringFromIndex:1];
}
if (rangeDoubleComma.location != NSNotFound) {
self.selectedString = [self.selectedString stringByReplacingOccurrencesOfString:#",,"
withString:#","];
}
But This is a very dirty approach, can any one suggest a good approach for this.

Answer 1

You could do something like this
NSString *str = #"aaa,bbb,ccc";
NSMutableArray *arr = [[str componentsSeparatedByString:#","] mutableCopy];
int indexToRemove = -1;
for (int i = 0; i < arr.count; i++) {
NSString *string = [arr objectAtIndex:i];
if([string isEqualToString:#"aaa"])
{
indexToRemove = i;
break;
}
}
if(indexToRemove != -1)
{
[arr removeObjectAtIndex:indexToRemove];
}
NSString *newString = [arr componentsJoinedByString:#","];

Answer 2

Do you need to store this comma separated list as a string? Instead, try maintaing an NSArray/NSMutableArray of NSString's. That makes it easy to add or remove any item at will. When you need the comma-separated string representation of the array, just do:
[self.selectedArray componentsJoinedByString:#","]
If you'd like to still use your self.selectedString property, just put the above line of code in a getter method:
- (NSString *) selectedString {
return [self.selectedArray componentsJoinedByString:#","]
}