How to use protocol instead of delegate in iPhone

Question

Scenario: Need to execute CustomWebview delegate on view controller.

Please help me with this code. Instead of using callback, I need to use "Protocol". Can it be done or we can only use callback in this scenario.

On ViewController.m

- (void)viewDidLoad {
[super viewDidLoad];
//MyWebView *webView = [[MyWebView alloc] initWithDelegate:self callback:@selector(finishLoading)];

MyWebView *webView= [[MyWebView alloc] initWithFrame:CGRectMake(0,0,320, 460)];
[webView LoadURL:@"http://192.168.5.165/"];
[webView setDelegate:self];
[webView setCallback:@selector(finishLoading)];
[self.view addSubview:webView] ; 

} - (void) finishLoading {

NSLog(@"Finish");

}

---

On MyWebView.h

@interface MyWebView : UIView<UIWebViewDelegate> {
    NSString *strURL;
}
@property(nonatomic, retain) NSString *strURL;
@property (nonatomic, assign) id delegate;
@property (nonatomic, assign) SEL callback;

-(void) LoadURL:(NSString*)url;
@end

On MyWebView.m

#import "MyWebView.h"

@implementation MyWebView
@synthesize strURL,delegate,callback;
UIWebView *webView;
-(id) initWithFrame:(CGRect)frame
{
    if(self =[super initWithFrame:frame])
    {
        webView = [[UIWebView alloc] initWithFrame:frame];
        webView.delegate = self;
        [self addSubview:webView];

    }
    return self;
}

-(void) LoadURL:(NSString*)url
{
    NSURL *u = [NSURL URLWithString:url];
    NSURLRequest *req= [NSURLRequest requestWithURL:u];
    [webView loadRequest:req];
}

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    [delegate performSelector:callback];
}

Answer 1

Your question is a bit unclear. A protocol and a delegate are two entirely separate, though related, things--apples and oranges. A protocol defines a list of methods an object may or must respond to:

@protocol Document
+ (id)documentWithContentsOfURL: (NSURL *)aURL;
- (void)writeToURL: (NSURL *)aURL error: (NSError **)outError;
@end

A delegate is an object, usually an instance of a custom class, that is handed to another object for custom processing or feedback--that latter object delegates work to the delegate object.

---

Are you asking how to convert a delegate category on NSObject to a delegate protocol? (The former used to be Apple's pattern for defining the obligations and abilities of a delegate; the latter is the newer way to do the same thing.) If so, it generally looks something like this:

Delegate Category on NSObject

@interface NSObject (WidgetDelegate)
- (void)doSomethingWithWidget: (Widget *)w;
@end

@interface Widget : NSObject
@property (readwrite, assign) id delegate;
@end

Delegate Protocol

@protocol WidgetDelegate <NSObject>
- (void)doSomethingWithWidget: (Widget *)w;
@end


@interface Widget : NSObject
@property (readwrite, assign) id <WidgetDelegate> delegate;
@end

Is that what you're looking for? If not, can you clarify exactly what you're trying to do?