Accessing a method on a views superview - What is

Question

My problem is a follows

I have a UIViewController subclass which holds a UISegmentedController and four tableviews that I layed out in interface builder.

@interface MultiTableHoldingView : UIViewController{

}

@property (strong, nonatomic) IBOutlet DataTV *dsDataTV;
@property (strong, nonatomic) IBOutlet EnviroTV *dsEnvironmentTV;
@property (strong, nonatomic) IBOutlet LocationTV *dsLocationTV;
@property (strong, nonatomic) IBOutlet Note_AnimalTV *dsNoteAnimal;

@property (strong, nonatomic) IBOutlet UISegmentedControl *diveElementSegmentController;

@property (strong, nonatomic) DiveSite* currentSite;

- (IBAction)diveElementSegmentControllerDidChange:(UISegmentedControl *)sender;

-(void) setFreshWaterColor;
-(void) setSaltwaterColor;

@end

setFreshWaterColor and setSaltWaterColour just set the background colour properties of the MultiTableHoldingView instances UIView and the four tableviews it contains. Both these method work fine when called from MultiTableHoldingView's viewDidLoad method. Heres one of them

-(void) setSaltwaterColor{

    DLog(@"in set salt water colour");
    self.view.backgroundColor= SaltWaterColor;
    _dsLocationTV.backgroundColor=SaltWaterColor;
    _dsDataTV.backgroundColor=SaltWaterColor;
    _dsEnvironmentTV.backgroundColor=SaltWaterColor;
    _dsNoteAnimal.backgroundColor=SaltWaterColor;

}

The other is the same except sets to FreshWaterColor - both are #define i have set up.

I use the segmentedController to turn the hidden properties of the various tableviews on and off. All nice and simple. The tableviews are pulling in their data. Working fine.

When selecting one of my tableview cells on one of the tableViews I want to change the background colour of both my tableview ( in fact all of my tableviews ) and the UIView that is the superview

self.superview.backgroundColor = FreshWaterColor;

works fine for reaching back and changing the instance of MultiTableHoldingView views background property but I want to call the instance of MultiTableHoldingView's setFreshWaterColor and setSaltwaterColor methods.

I have imported MultiTableHoldingViews header into the relevant tableview (EnviroTV), so it knows about it its superviews methods. But if I try to call either of the two methods on self.superview the methods do not show up and if i type them in full I get an the following error

no visible interface for 'UIView' shows the selector 'setFreshWaterColor'

So i checked what kind of object the superview was and its a "class of superview UIViewControllerWrapperView"

I search on this and its apparently "

This is a private view used by the framework. You're not supposed to modify it or whatsoever."

I'm obviously missing something here - how should i call the method on the instance of MultiTableHoldingView ?

Thanks in advance

Simon

Doh - its just delegation as danypata mentions in the comments - i've posted exactly how I did this as an answer below. Tried to make it as clear as possible how delegation works

Answer 1

THE SOLUTION

Step one - get more sleep before coding .

This really is basic objective-c stuff - I just went off at a tangent, looking for someway else to do it, getting confused by my discovery of UIViewControllerWrapperView along the way.

The solution, as danypata rightly suggests in the comments, is to use delegate -a common design pattern in Objective-C - just like you do, for example, when you use another class to supply tableview data

As I've been a numpty and wasted hours of my time today I'll try and make the 'how' clear for other relative newbies or people having an off day and not thinking straight.

In my case I set this up as follows

In my subview class's interface file - EnviroTV.h - I define the following protocol just before the @interface declaration

@protocol EnviroTVProtocol <NSObject>


-(void) setFreshWaterColor;
-(void) setSaltwaterColor;


@end

Then in the @interface section of the same file I add a property of type id which must conform the protocol I just declared .

@property (nonatomic, strong ) id<EnviroTVProtocol> colorChangeDelegate;

You make the type an id - a generic object - as you really don't care what kind of object is going to act as your delegate just that it implement the methods that you need it to run. When an object declares itself to implement a protocol its just promising to implement the method(s) that are required by the protocol

So, when I want to run the methods on the superviews class I call

[self.colorChangeDelegate setFreshWaterColor];

Or

[self.colorChangeDelegate setSaltWaterColor];

The final piece of the delegation pattern is to go into the class thats going to be the delegate (in this case my MultiTableHoldingView class ) and state that it conforms to the protocol

I do this in the MultiTableHoldingView.h file

Changing this line :

@interface MultiTableHoldingView : UIViewController

into this line :

@interface MultiTableHoldingView : UIViewController <EnviroTVProtocol>

means this class promises to implement all the required methods of the EnviroTVProtocol.

Luckily I had already written the two methods. So when I compiled it ran correctly

Newbies - don't be afraid of delegation - its awesome and not as complex as you first imagine it to be

Meanwhile, if anyone can explain what UIViewControllerWrapperView is .....