Checks if the Alex voice is installed on iOS.

checkForAlex.m

- (void)checkForAlex {
    
    // is Alex installed?
    BOOL alexInstalled = NO;
    NSArray *voices = [AVSpeechSynthesisVoice speechVoices];
    
    for (id voiceName in voices) {
        
        if ([[voiceName valueForKey:@"name"] isEqualToString:@"Alex"]) {
            alexInstalled = YES;
        }
    }
    
    if (alexInstalled) {
        NSLog(@"Alex is installed on this device.");
    } else {
        NSLog(@"Alex is not installed on this device.");
    }
}