如何在NSString中获得一些选定的字符？

Question

My NSString Value is

 NSString * string = @"A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";

And i want to develop one method

- (void)viewDidLoad {
    [super viewDidLoad];
    [self getAlphabetsBasedOnNumber:2];

}

-(void)getAlphabetsBasedOnNumber :(int)number{

}

and I want a result like below:

When sending 1 : output:ACEGI(Leave one character).
When Sending 2 : output:ADGJM(Leave two charaters).

Answer 1

OK, I think I understand it now.

Your method should be something like this...

- (NSString *)stringFromAlphabetBySkippingLetters:(NSInteger)skip
{
    NSArray *letters = [@"A", @"B", @"C", @"D", @"E", ...

    NSMutableString *result = [NSMutableString string];

    for (int i=0 ; i<letters.count ; i += 1 + skip) {  // 1 + skip because a value of 1 will actually jump two places each time
        [result append:letters[i]];
    }

    return result;
}

This is very basic stuff though. You should really have a go at this yourself before resorting to StackOverflow.

As Rob pointed out. If you have a string of comma separated letters then you can convert that to an array by using...

NSArray *letters = [theString componentsSeparatedByString:@","];