根据字符串范围返回布尔值

Question

I'm trying to find the string "wolf" in a NSArray and the return back the Boolean value of YES or NO if the word exists or not. I'm having trouble returning the YES or NO. My initial thought was to assign an NSInteger or NSNumber to a 1 or a 0 but I can't seem to initialize either properly outside of my if/else statement. Any help? Thanks guys.

Here's my code:

- (BOOL) characterArrayContainsWorf:(NSArray *)characterArray {

NSNumber *characterExistance;

for (NSString* character in characterArray) {

    if ([character rangeOfString:@"wolf" options:NSCaseInsensitiveSearch].location != NSNotFound) {

    } else {

    }
}

return RETURN BOOLEAN HERE;

}

Answer 1

Return YES if you find it, otherwise return NO after the for-loop if you don't.

- (BOOL)characterArrayContainsWolf:(NSArray *)characterArray {
    // loop through the array of characters
    for (NSString *character in characterArray) {
        // if you find the wolf, return that you found the wolf
        if ([character rangeOfString:@"wolf" options:NSCaseInsensitiveSearch].location != NSNotFound) {
            return YES;
        }
    }

    // if you get here that means you iterated through each string in
    // the array and none of them contained 'wolf'
    return NO;   
}

For completeness, this is an alternative method that does what you were questioning, creating a variable outside the loop and setting it inside the loop:

- (BOOL)characterArrayContainsWolf:(NSArray *)characterArray {
    // initialize the BOOL to no to start
    BOOL didFindWolf = NO;

    // loop through the array of characters
    for (NSString *character in characterArray) {
        // if you find the wolf, set that you found the world and break,
        // stopping the for-loop
        if ([character rangeOfString:@"wolf" options:NSCaseInsensitiveSearch].location != NSNotFound) {
            didFindWolf = YES;
            break;
        }
    }

    // this will be YES if we found it, or NO if we didn't
    return didFindWolf;
}

This seems to be a fantastic opportunity to demonstrate how a simple unit test can help you feel much more confident about your new code:

- (void)testWolfSearch {
    NSArray *emptyArray = @[];
    NSArray *nilArray = nil;
    NSArray *noWolfHere = @[@"apple", @"maserati", @"The Spriggan", @"Oedipus Rex"];
    NSArray *almostWolf = @[@"Wol", @"olf", @"w"];
    NSArray *onlyWolf = @[@"wolf"];
    NSArray *onlyWolfCapital = @[@"WOLF"];
    NSArray *containsWolf = @[@"omfg", @"Why am I doing this?", @"wolf", @"The cake is a lie..."];
    NSArray *containsVersionOfWolf = @[@"Gregory", @"WOLFENSTEIN", @"Rubbish"];
    NSArray *containsManyWolves = @[@"wolf", @"wolf", @"DAT WOLF DOE", @"WOLF"];

    XCTAssertFalse([self characterArrayContainsWolf:emptyArray], @"An empty array should return NO.");
    XCTAssertFalse([self characterArrayContainsWolf:nilArray], @"A nil array should return NO.");
    XCTAssertFalse([self characterArrayContainsWolf:noWolfHere], @"An array with multiple values that doesn't contain wolf should return NO.");
    XCTAssertFalse([self characterArrayContainsWolf:almostWolf], @"An array with values close to Wolf, but not, should return NO.");
    XCTAssertTrue([self characterArrayContainsWolf:onlyWolf], @"An array containing a single string that matches should return YES.");
    XCTAssertTrue([self characterArrayContainsWolf:onlyWolfCapital], @"An array containing a single string that matches and it all caps, should return YES.");
    XCTAssertTrue([self characterArrayContainsWolf:containsWolf], @"An array containing many values, one of which is wolf, should return YES.");
    XCTAssertTrue([self characterArrayContainsWolf:containsVersionOfWolf], @"An array that contains a string with wolf as a substring should return YES.");
    XCTAssertTrue([self characterArrayContainsWolf:containsManyWolves], @"An array that contains many versions of the wolf string should return YES.");
}