Unrecognised selector sent to instance of UIViewController (or protocol)? - ios

Question

I'm quite new to iOS dev, I met this problem while i'm trying to embed an open source Wheel Rotating project (https://github.com/funkyboy/How-To-Create-a-Rotating-Wheel-Control-with-UIKit) into mine.
Basically, I copied the relevant code files and assets from this open source project into mine, and did some necessary changes, hope it will run.
The "Rotary Wheel Component" were from the original opensource project, and the "Mood Roulette" is my project.
Here's the screen shot of the project's structure:
And the stacktrace:
2014-03-10 13:06:12.865 Mood Roulette[13125:60b] cl is 7 | 0.392699, 0.785398, 1.178097
2014-03-10 13:06:12.866 Mood Roulette[13125:60b] -[UCViewController wheelDidChangeValue:]: unrecognized selector sent to instance 0x146d175f0
2014-03-10 13:06:12.869 Mood Roulette[13125:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UCViewController wheelDidChangeValue:]: unrecognized selector sent to instance 0x146d175f0'
*** First throw call stack:
(0x18ba1f09c 0x19799dd78 0x18ba23d14 0x18ba21a7c 0x18b9414ac 0x1000c05fc 0x1000bfb44 0x1000c26f4 0x18e8f42c0 0x18e8f4044 0x18e8fb7dc 0x18e8f8ab0 0x18e96c88c 0x18e9691f0 0x18e9629a0 0x18e8f5530 0x18e8f4720 0x18e9620b0 0x191345128 0x191344c54 0x18b9defc8 0x18b9def28 0x18b9dd14c 0x18b91db38 0x18e9612d4 0x18e95c0e8 0x1000c24b8 0x197f87aa0)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
======
The error point is on the line 100
[self.delegate wheelDidChangeValue:[self getCloveName:currentValue]];
of the code:
https://github.com/funkyboy/How-To-Create-a-Rotating-Wheel-Control-with-UIKit/blob/master/RotaryWheelProject/SMRotaryWheel.m
Here's the part I've changed (Mainly the changes were made in ViewControllers):
UCAppDelegate.h:
#import <UIKit/UIKit.h>
//#class UCViewController;
#interface UCAppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
//#property (strong, nonatomic) UCViewController *viewController;
#end
UCAppDelegate.m:
#implementation UCAppDelegate
//#synthesize window;
//#synthesize viewController;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
// self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// self.window.rootViewController = self.viewController;
// [self.window makeKeyAndVisible];
return YES;
}
UCViewController.h
#import <UIKit/UIKit.h>
#import "SMRotaryProtocol.h"
#interface UCViewController : UIViewController
#property (nonatomic, strong) UILabel *valueLabel;
#end
UCViewController.m:
#import "UCViewController.h"
#import "SMRotaryWheel.h"
#interface UCViewController ()
#end
#implementation UCViewController
#synthesize valueLabel;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
valueLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, 350, 120, 30)];
valueLabel.textAlignment = NSTextAlignmentCenter;
valueLabel.backgroundColor = [UIColor lightGrayColor];
[self.view addSubview:valueLabel];
SMRotaryWheel *wheel = [[SMRotaryWheel alloc] initWithFrame:CGRectMake(0, 0, 200, 200)
andDelegate:self
withSections:8];
wheel.center = CGPointMake(160, 240);
[self.view addSubview:wheel];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
The project will build without any problems, but will leave a black screen and give a unrecognised selector error while running.
Is there anything I also need to change?
Thanks for any help.

Answer 1

You don't have an actual implementation of the method wheelDidChangeValue: in your UCViewController, from what you've posted. So, when that method is called at runtime, there's no method to "catch" the call, which causes the error you're seeing.

Answer 2

I think you have to set the delegate of the SMRotaryWheel class:
#import <UIKit/UIKit.h>
#import "SMRotaryProtocol.h"
#interface UCViewController : UIViewController <SMRotryWheelDelegate>
#property (nonatomic, strong) UILabel *valueLabel;
#end
ATTENTION: I actually don't know how the Delegate is called
And then don't forget to implement the delegate methods.