How to test if an NSArray or NSSet contains an object

There’s a handy method in the NSArray class that lets us check if an array contains a particular object or not. The containsObject method returns a BOOL for us to evaluate.

Consider this:

// create an array
NSArray *array = @[@"Apples", @"Pears" , @"Bananas"];

// check if Pears are in the array
if ([array containsObject:@"Pears"]) {
    NSLog(@"We have Pears.");

Likewise, we can check if our array does not contain a particular object by testing the opposite:

// check if Grapes are not in the array
if (![array containsObject:@"Grapes"]) {
    NSLog(@"But we don't have Grapes.");

Both the NSMutableArray and NSSet classes has the same method, so we can check for the (un-)presence of our objects in mutable arrays and sets the same way.

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