View Delegate Not Being Called - ios

Question

I'm building a graphing app, and I have a view and a view controller, which acts as a delegate for the view (to retrieve information). While I haven't started the actual drawing yet, I am currently trying to store values in a dictionary; however, I have certain NSLogs placed methodically across the view controller and I noticed that the delegate methods I call from the view don't get called at all. For example, I call my scaleForGraph function, but it does not execute. Being new to this, I'm not sure if there's something I'm missing. FYI: I have no errors, it compiles and executes. I've tried to slim the code down as much as possible. Thank you for your help!
Here's the .h for my view, where I define the protocol:
// GraphView.h
#import <UIKit/UIKit.h>
#class GraphView;
#protocol GraphViewDelegate <NSObject>
- (float)scaleForGraph:(GraphView *)requestor;
-(NSMutableDictionary*) valuesForGraph:(GraphView *)requestor withWidth:(float) width;
#end
#interface GraphView : UIView
#property (nonatomic) id <GraphViewDelegate> delegate;
#property (nonatomic) id expressionCopy;
#end
And here's the .m:
#import "GraphView.h"
#implementation GraphView
#synthesize expressionCopy = _expressionCopy;
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
self.contentMode = UIViewContentModeRedraw;
}
return self;
}
- (void)awakeFromNib
{
self.contentMode = UIViewContentModeRedraw;
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
CGContextRef c = UIGraphicsGetCurrentContext();
CGRect screenBound = [[UIScreen mainScreen] bounds];
CGSize screenSize = screenBound.size;
CGFloat width = screenSize.width;
CGFloat height = screenSize.height;
float scale = [self.delegate scaleForGraph:self];
NSLog([NSString stringWithFormat:#"My Scale: %f",scale]); //always returns 0
NSMutableDictionary *graphValues = [self.delegate valuesForGraph:self withWidth:width];
}
#end
And here's my view controller .h:
#import <UIKit/UIKit.h>
#import "GraphView.h"
#interface GraphingViewController : UIViewController <GraphViewDelegate>
#property (weak, nonatomic) IBOutlet GraphView *graphView;
#property (strong, nonatomic) IBOutlet UIStepper *stepper;
- (IBAction) changedScale:(UIStepper *)stepper;
#property (nonatomic) int scale;
#property (nonatomic) id expressionCopy;
#end
And here's the .m for the controller:
#import "GraphingViewController.h"
#interface GraphingViewController ()
#end
#implementation GraphingViewController
#synthesize expressionCopy = _expressionCopy;
- (void)updateUI
{
self.stepper.value = self.scale;
[self.graphView setNeedsDisplay];
}
- (void)setScale:(int)scale
{
if (scale < 0) scale = 0;
if (scale > 100) scale = 100;
_scale = scale;
[self updateUI];
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(IBAction)changedScale:(UIStepper *)stepper {
self.scale = stepper.value; //this function works fine, but is not delegate/does not get called by view
}
-(float) scaleForGraph:(GraphView *)requestor {
NSLog(#"HI"); //never gets here
}
-(NSMutableDictionary*) valuesForGraph:(GraphView *)requestor withWidth:(float) width {
NSLog(#"Hello2"); //never gets here
}
return xyVals;
}
#end

Answer 1

Nowhere in the code you've posted do you tell your GraphView that the GraphingViewController is it's delegate. So, you are sending a message to nil.
You'll want to do something like:
self.graphView.delegate = self;
In your GraphingViewController setup code.

Answer 2

Make your controller actual delegate of GraphView. You can do it in interface builder by Ctrl-dragging from GraphView to the object (orange circle in the bottom) and than choose "delegate"