Implementing delegate methods for modal view contr

问题:

I have a simple project to present a modal view controller and transfer back a string based on which button in the modal VC that gets pressed. I based it all on watching the Stanford class on iTunes U. It looks like I have everything correct, but I get a couple of compiler warnings.

First I get one called passing argument 1 of 'setDelegate:' from incompatible pointer type in TransferViewController.m

Second I get four warnings called Invalid receiver type 'id <MyModalViewControllerDelegate>*' but these aren't displayed in the build results area, rather next to the offending lines in MyModalViewController.m, both lines in each of the button actions.

Here's the code...

//  TransferViewController.h

#import <UIKit/UIKit.h>
#import "MyModalViewController.h";

@interface TransferViewController : UIViewController <MyModalViewControllerDelegate> {
    UILabel *label;
    UIButton *button;
}

@property (nonatomic, retain) IBOutlet UILabel *label;
@property (nonatomic, retain) UIButton *button;

- (IBAction)updateText;

@end

---

//  TransferViewController.m

#import "TransferViewController.h"

@implementation TransferViewController

@synthesize label;
@synthesize button;

- (IBAction)updateText {
    MyModalViewController *myModalViewController = [[MyModalViewController alloc] init];
    myModalViewController.delegate = self; // I get the warning here.
    [self presentModalViewController:myModalViewController animated:YES];
    [myModalViewController release];
}

- (void)myModalViewController:(MyModalViewController *)controller didFinishSelecting:(NSString *)selectedDog {
    label.text = selectedDog;
    [self dismissModalViewControllerAnimated:YES];
}

@end

---

//  MyModalViewController.h

#import <UIKit/UIKit.h>

@protocol MyModalViewControllerDelegate;

@interface MyModalViewController : UIViewController {
    UIButton *abby;
    UIButton *zion;
    id <MyModalViewControllerDelegate> delegate;
}

@property (assign) id <MyModalViewControllerDelegate> delegate;

- (IBAction)selectedAbby;
- (IBAction)selectedZion;

@end

@protocol MyModalViewControllerDelegate <NSObject>

@optional

- (void)myModalViewController:(MyModalViewController *)controller didFinishSelecting:(NSString *)selectedDog;

@end

---

//  MyModalViewController.m

#import "MyModalViewController.h"

@implementation MyModalViewController

@synthesize delegate;

- (IBAction)selectedAbby {
    if ([self.delegate respondsToSelector:@selector (myModalViewController:didFinishSelecting:)]) {
        [self.delegate myModalViewController:self didFinishSelecting:@"Abby"];
    }
}

- (IBAction)selectedZion {
    if ([self.delegate respondsToSelector:@selector (myModalViewController:didFinishSelecting:)]) {
        [self.delegate myModalViewController:self didFinishSelecting:@"Zion"];
    }

}

回答1:

Get rid of those *s after id <something> and before delegate.

So make this

id <MyModalViewControllerDelegate> *delegate;

this

id <MyModalViewControllerDelegate> delegate;