[objective-c]about NSMutableArray

Question

ruby code(irb)

irb(main):001:0> ary = ["AAA", "BBB", "CCC"]
=> ["AAA", "BBB", "CCC"]
irb(main):003:0> ary.index("AAA")
=> 0
irb(main):004:0> ary.index("BBB")
=> 1
irb(main):005:0> ary.index("CCC")
=> 2
irb(main):006:0> ary.index("DDD")
=> nil

I want to do same in objective-c(NSMutableArray).

Answer 1

Read Apple’s documentation for NSArray and NSMutableArray.

Answer 2

NSMutableArray *ary = [NSMutableArray arrayWithObjects:@"AAA",@"BBB",@"CCC",nil];
NSLog([ary description]);
NSInteger ndx = [ary indexOfObjectIdenticalTo:@"AAA"];
NSLog(@"%i",ndx);
ndx = [ary indexOfObjectIdenticalTo:@"BBB"];
NSLog(@"%i",ndx);
ndx = [ary indexOfObjectIdenticalTo:@"CCC"];
NSLog(@"%i",ndx);
ndx = [ary indexOfObjectIdenticalTo:@"DDD"];
NSLog(@"%i",ndx);

Cocoa methods are all pretty self explanatory, so skimming the headers can help you solve almost any problem.

EDIT: changed from NSArray to NSMutableArray, added note:

Note: the last method returns -1, not nil.