The previous answers mentioning [[UIView appearance] setTintColor:[UIColor redColor]];
should work but this code is doing way more than if should if you want to change only the UIAlertView
tint color.
You can aim the component this way on iOS < 9 :
[[UIView appearanceWhenContainedIn:[UIAlertView class], nil] setTintColor:[UIColor redColor]];
[[UIView appearanceWhenContainedIn:[UIAlertController class], nil] setTintColor:[UIColor redColor]];
And on iOS >9 :
[[UIView appearanceWhenContainedInInstancesOfClasses:@[[UIAlertView class]]] setTintColor:[UIColor redColor]];
[[UIView appearanceWhenContainedInInstancesOfClasses:@[[UIAlertController class]]] setTintColor:[UIColor redColor]];