Custom UIView delegate not detecting touchesBegan - objective-c

Question

I did my research but haven't found an answer to the following problem: I have a custom delegate –subclass of UIView– and for some reason touchesBegan isn't working in the delegate implementation.
TestView.h
#import <UIKit/UIKit.h>
#class TestView;
#protocol TestViewDelegate <NSObject>
#end
#interface TestView : UIView
#property (assign) id <TestViewDelegate> delegate;
#end
TestView.m
#import "TestView.h"
#implementation TestView
#synthesize delegate = _delegate;
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch detected on TestViewDelegate");
}
#end
ViewController.h
#import <UIKit/UIKit.h>
#import "TestView.h"
#interface ViewController : UIViewController<TestViewDelegate>
#end
ViewController.m
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
UILabel* title = [[UILabel alloc] initWithFrame:CGRectMake(20, 30, 280, 40)];
[title setFont:[UIFont fontWithName:#"Helvetica-Bold" size:30]];
[title setTextColor:[UIColor blackColor]];
[title setTextAlignment:UITextAlignmentCenter];
[title setBackgroundColor:[UIColor clearColor]];
[tile setText:#"Test"];
[self.view addSubview:title];
}
- (void)viewDidUnload
{
[super viewDidUnload];
}
#end
What am I missing to make sure touchesBegan from TestView.m gets called when touches occur in ViewController.m?

Answer 1

Your last line indicates a fundamental misunderstanding of views and view controllers. Touches don't occur in view controllers; touches occur in views. After a view is touched, it tells its controller that it was touched, and the controller does something with this information. The way that it does this is through a pattern called delegation.
So let's go through this piece by piece. In order to get what you want, you would have to do the following:
First: create an instance of TestView and add it as a subview of the view controller's view.
Now the view exists, and when you tap it you will see your "Touch detected on TestViewDelegate" logged to the console. But it won't actually do anything with the delegate (there isn't even a delegate yet!).
Second: set the newly created TestView's delegate property to the view controller. Do this after you create the TestView instance but before you add it to the view hierarchy.
Now they're hooked up a little, but the view is never talking to its delegate (this doesn't happen automatically; when you create a delegate protocol you have to specify what messages the view will be able to send it).
Third: add a method to the TestViewDelegate protocol and implement that method in the view controller. This could be something like touchesBeganOnTestView:(TestView *)sender, or whatever else you want the view to tell the delegate when it's touched. That looks like this:
#class TestView;
#protocol TestViewDelegate <NSObject>
- (void)touchesBeganOnTestView:(TestView *)sender;
#end
You have to add the #class line because the protocol declaration comes before the declaration of TestView -- at that point in the file, the compiler doesn't know what "TestView" means, so to avoid a warning you say "don't worry, I'm going to declare this later."
Fourth: invoke that method from TestView's touchesBegan. This is as simple as adding the line [self.delegate touchesBeganOnTestView:self];.
That'll get you what you want. From your question I'm gathering that you're pretty new to iOS/Objective-C, and it's going to be difficult if you don't have a solid understanding of the fundamentals. A good place to start might be Apple's description of delegation.