I had been using following code to change text color of items which I add in UIActionSheet.:
- (void)willPresentActionSheet:(UIActionSheet *)act         
        I have same task and I've made this hack today, dirty, but it works
class CustomAlertViewController: UIAlertController {
    internal var cancelText: String?
    private var font: UIFont? = UIFont(name: "MuseoSansCyrl-500", size: 12)
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.tintColor = UIColor.blackColor()
    }
    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        self.findLabel(self.view) //if you need ios 9 only, this can be made in viewWillAppear
    }
    func findLabel(scanView: UIView!) {
        if (scanView.subviews.count > 0) {
            for subview in scanView.subviews {
                if let label: UILabel = subview as? UILabel {
                    if (self.cancelText != nil && label.text == self.cancelText!) {
                        dispatch_async(dispatch_get_main_queue(),{
                            label.textColor = UIColor.redColor() //for ios 8.x
                            label.tintColor = UIColor.redColor() //for ios 9.x
                        })
                    }
                    if (self.font != nil) {
                        label.font = self.font
                    }
                }
                self.findLabel(subview)
            }
        }
    }
}
Swift 4
    let alert =  UIAlertController(title: "title", message: "message", preferredStyle: .alert)
    alert.view.tintColor = UIColor.black
    self.present(alert, animated: true, completion: nil)
Ok, I ran into the same problem but I think I have found a solution:
The appropriate way should be like this and I guess it works in iOS7:
[[UIButton appearanceWhenContainedIn:[UIActionSheet class], nil] setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
But it will not work in iOS8 due to the fact that the ActionSheets "buttons" is now based on a UICollectionView. So after some digging around I got this to work instead:
[[UICollectionView appearanceWhenContainedIn:[UIAlertController class], nil] setTintColor:[UIColor blueColor]];