CODEWITHSUNDEEP
objective-cnsmutablearray
user1418214
user1418214

Reputation: 59

Assign values to NSMutable Array within for loop

I am trying to write a method for a new class called "word", which is a subclass of NSString. I want a method that will accept a NSString containing a single character and return the the place within the word of every instance of that string. I have this so far:

@implementation Word
    -(NSMutableArray *)placeOfLetter: (NSString *)letterAsked;{
        NSUInteger *len=(NSUInteger *)[self length];
        int y=0;
        char letter=(char)letterAsked; 

        for (NSUInteger *x=0; x<len; x++) {
                if ([self characterAtIndex:*x]==letter){
                     [matchingLetters insertObject:x atIndex:y];
                     y++;
                }
        }
    }     
@end

however, xcode is telling me that I cannot put x as a the parameter for insertObject, because the "implicit conversion from NSUInteger to id is disallowed. How can I get around this?

Upvotes: 0

Views: 133

Answers (2)

rob mayoff
rob mayoff

Reputation: 385500

NSUInteger is a typedef for either unsigned int or unsigned long, depending on your platform. It is not an object type. So when you declare NSUInteger *x=0, you're declaring x as a pointer-to-unsigned-integer, and initializing it to null.

The insertObject:atIndex: requires an NSUInteger, not an NSUInteger*, as its index argument.

Just take out the * from the for statement and the characterAtIndex: message.

You do have other problems in your method also, like casting letterAsked to a char instead of getting the character out of it using characterAtIndex: and declaring len as a pointer.

Upvotes: 1

Tim
Tim

Reputation: 60110

The problem you're encountering is stemming mostly from your treating NSUInteger as a pointer; you have some other casting problems as well. Try the following:

  • Instead of taking a full string for the letterAsked argument, then getting a char out of it, just get a char (or unichar) as your argument to begin with. You avoid the letter = (char)letterAsked conversion altogether.

  • Don't make len a pointer. You may not need to declare len at all. Consider writing your for loop like:

    for(NSUInteger x = 0; x < [self length]; x++) { // ...

    This also helps you in the -characterAtIndex: call; you no longer need to dereference x in order to get the character.

  • Like Hot Licks said in the comments, use an NSNumber if you want a position inside an NSArray; you need numbers to be class instances to go in an NSArray instance. You can create an NSNumber out of x like this:

    NSNumber * foundPosition = [NSNumber numberWithUnsignedInteger:x];

  • Consider just using NSMutableArray's -addObject: method, rather than keeping track of y and incrementing it each time. You'll get the same result.

Upvotes: 2

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