Modified button images lost during seque - ios

Question

I have three scenes (viewControllers) linked through modal segues (I don't want a navigation controller). The view has a series of buttons, each initially with a red-light image. When clicked they go to the next scene, whose action may affect the image on the preceding scene by making it a yellow or green light image.
If the button image is changed programmatically via setImage, and later if the button is clicked again, the button image always reverts to the initial red-light image. Similarly if I change the button images on scene 2, go back to scene 1, and then back to scene 2 again, the buttons are back to default, rather than retaining the previous button image state.
So, the two basic questions are:
How to prevent the button image from changing back to default when clicked.
How to have an visited scene remember it's previous settings rather than go back to initial settings when visited a second time.
Thanks,
Ray

Answer 1

If you're using modal transitions, you need to use dismissViewControllerAnimated:completion: to get back. I'm guessing that instead you're pushing from VC1 to VC2, and then pushing a new copy of VC1 in order to return, which is wrong.

Answer 2

1 question: Please, show your code for changing images, mb problem in it.
2 question: My answer for second question is make a manager for your button states, for example like below:
.h
NS_ENUM(NSInteger, LightState) {
LightStateRed,
LightStateYellow,
LightStateGreen
};
#interface LightManager : NSObject
+ (instancetype)sharedManager;
- (NSString *)imageForButtonNumber:(int)buttonNumber;
- (void)changeImageForButtonNumber:(int)buttonNumber;
#end
.m
#implementation LightManager {
NSMutableArray *buttonStates;
NSArray *images;
}
+ (instancetype)sharedManager {
static LightManager *sharedManager;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedManager = [[LightManager alloc] init];
});
return sharedManager;
}
- (id)init {
self = [super init];
if (self) {
images = #[#"red_light", #"yellow_light", #"green_light"]; // Or whatever images have names in your app
buttonStates = [[NSMutableArray alloc] initWithCapacity:9000]; // Number of all buttons
for (int index = 0; index < 9000; index++) {
[buttonStates addObject:#(LightStateRed)]; // Initalize with default value
}
}
return self;
}
- (NSString *)imageForButtonNumber:(int)buttonNumber { // For restoring previous state
return images[[buttonStates[buttonNumber] integerValue]];
}
- (void)changeImageForButtonNumber:(int)buttonNumber { // On button click
if ([buttonStates[buttonNumber] integerValue] == LightStateGreen) { // If you want looping
buttonStates[buttonNumber] = #(LightStateRed);
}
else {
buttonStates[buttonNumber] = #([buttonStates[buttonNumber] integerValue] + 1);
}
}
#end
Or make manager from your first controller and pass states to modal controller through -initWithParams: and save back in first controller via delegate methods or whatever.