How to wait for button press in objective c - ios

Question

I have an array of objects (scaleNotes) that are assigned to buttons that I would like to iterate through. I want the app to wait for the first set of buttons to be pressed, then to wait for the second, and so on. However, with the function I currently have the app freezes.
The method that contains the array:
-(void)fingerScale :(UIButton*)button1 :(UIButton*)button2 :(UIButton*)button3 :(UIButton*)button4 :(UILabel*)label {
Note *note = [[Note alloc]init];
for (int i = 0; i < [_scaleNotes count]; i++) {
note = _scaleNotes[i];
label.text = note.noteName;
[note waitForNote:button1 :button2 :button3 :button4 :note];
NSLog(#"Waiting... %i", i);
}
}
The "waitForNote" method:
-(void)waitForNote:(UIButton *)button1 :(UIButton *)button2 :(UIButton *)button3 :(UIButton *)button4 :(Note*)Note {
bool loop = YES;
while (loop) {
switch ([Note.fingering count]) {
case 0:
loop = NO;
break;
case 1:
button1 = Note.fingering[0];
if (button1.touchInside) {
loop = NO;
}
break;
case 2:
button1 = Note.fingering[0];
button2 = Note.fingering[1];
if (button1.touchInside && button2.touchInside) {
loop = NO;
}
break;
case 3:
button1 = Note.fingering[0];
button2 = Note.fingering[1];
button3 = Note.fingering[2];
if (button1.touchInside && button2.touchInside && button3.touchInside) {
loop = NO;
}
break;
default:
break;
}
}
}
I have been told that using addTarget:action:forControlEvents may solve my problem instead of using a while loop, but I am unsure about how to implement that into my code. Please help.

Answer 1

Your while loop is an infinite loop, and that's why your app appears to freeze. Most GUI systems -- iOS included -- won't work that way. You have to give the app's event loop, or run loop, time to gather and process events.
-addTarget:action:forControlEvents: will be part of the solution, but you really need to spend some time learning more about how apps and controls work in general. Briefly, your controls should be connected to appropriate actions; if you want to enforce some order for the buttons you might enable or disable some buttons as necessary.

Answer 2

To expand on Caleb's answer a little bit:
iOS, like most modern interactive OS'es, is event-driven.
You write code that responds to events. The OS detects events, and then invokes the methods in your app that respond to those events.
You do NOT write a while loop that keeps looping, waiting for things to happen.
For buttons, you create methods of type IBAction, and you connect them to your buttons (usually connected to a "touch up inside" event.) Then, when the user taps and releases a button, the system calls your action method.
For a slider, you would write an action method and attach it to the "value changed" event for the slider. Then, when the user changed the value of the slider the system would call you.
So for your buttons you would write an action method and attach it to your buttons. (It's more common to create buttons and attach them to actions in Interface Builder, but you can also create them in code and then attach them using the -addTarget:action:forControlEvents: method you mentioned.)
If you've got multiple buttons that do the same thing but with different values, you might want to attach all the buttons to the same IBAction method, and then put different tag values on each button. Then in your IBAction method, look at the tag on the sender (The button that invoked the action) and use that to figure out which button was pressed.