Cant call delegate method from my protocol class

问题

I have a protocol in one class:

@protocol DataStorageManager

- (void) saveFile;

@end

@interface DataManager : NSObject
{
    id <DataStorageManager> delegate;
}

@property (nonatomic, assign) id<DataStorageManager> delegate;

//methods

@end

and its implementation:

@implementation DataManager

@synthesize delegate;

@end

and I have another class which is the adapter between the first and the third one:

#import "DataManager.h"
#import "DataPlistManager.h"

@interface DataAdapter : NSObject <DataStorageManager>

@property (nonatomic,strong) DataPlistManager *plistManager;
- (void) saveFile;

@end

and its implementation

#import "DataAdapter.h"

@implementation DataAdapter

-(id) initWithDataPlistManager:(DataPlistManager *) manager
{
    self = [super init];
    self.plistManager = manager;
    return self;
}

- (void) saveFile
{
    [self.plistManager savePlist];
}

@end

So when I in first method try to call my delegate method like this

[delegate saveFile];

Nothing happened. I don't understand what's wrong with the realization - it's a simple adapter pattern realization. So I need to use the delegate which will call the methods from the third class. Any help?

回答1:

You are not setting the delegate property. You need to do this,

-(id) initWithDataPlistManager:(DataPlistManager *) manager
{
    self = [super init];
    self.plistManager = manager;
    self.plistManager.delegate = self;
    return self;
}

Also, in DataManager class remove the ivar declaration, just declaring property is sufficient, the ivar gets automatically created. Call the delegate method as below,

if([self.delegate respondsToSelector:@selector(saveFile)] {
    [self.delegate saveFile]; 
}

Hope that helps!

回答2:

In your case you forget to set your protocol delegate and also need to call protocol method
by self.delegate....

I just Give Basic Idea for how to Create Protocol

Also Read This Question

#DetailViewController.h

#import <UIKit/UIKit.h>

@protocol MasterDelegate <NSObject>
-(void) getButtonTitile:(NSString *)btnTitle;
@end


@interface DetailViewController : MasterViewController

@property (nonatomic, assign) id<MasterDelegate> customDelegate; 

#DetailViewController.m

if([self.customDelegate respondsToSelector:@selector(getButtonTitile:)])
{
          [self.customDelegate getButtonTitile:button.currentTitle];    
}

#MasterViewController.m

create obj of DetailViewController

DetailViewController *obj = [[DetailViewController alloc] init];
obj.customDelegate = self;
[self.navigationController pushViewController:reportTypeVC animated:YES];

and add delegate method in MasterViewController.m for get button title.

#pragma mark -
#pragma mark - Custom Delegate  Method

-(void) getButtonTitile:(NSString *)btnTitle;
{
    NSLog(@"%@", btnTitle);

}

来源：https://stackoverflow.com/questions/18636874/cant-call-delegate-method-from-my-protocol-class

标签

ios

objective-c

adapter

delegation