如何创建自己的代理目标c中用户定义的委托[重复]

如何解决如何创建自己的代理目标c中用户定义的委托[重复]

||                                                                                                                   这个问题已经在这里有了答案：                                                      

解决方法

首先定义一个声明这样的委托-

@protocol IconDownloaderDelegate;

然后创建一个这样的委托对象-

@interface IconDownloader : NSObject
{
    NSIndexPath *indexPathInTableView;
    id <IconDownloaderDelegate> delegate;
    NSMutableData *activeDownload;
    NSURLConnection *imageConnection;
}

为它声明一个属性-

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

定义它 -

@protocol IconDownloaderDelegate 

- (void)appImageDidLoad:(NSIndexPath *)indexPath;

@end

然后，您可以在此委托上调用方法-

[delegate appImageDidLoad:self.indexPathInTableView];

这是图像下载器类的完整源代码- .h文件-

@class AppRecord;
@class RootViewController;

@protocol IconDownloaderDelegate;

@interface IconDownloader : NSObject
{
    AppRecord *appRecord;
    NSIndexPath *indexPathInTableView;
    id <IconDownloaderDelegate> delegate;

    NSMutableData *activeDownload;
    NSURLConnection *imageConnection;
}

@property (nonatomic,retain) AppRecord *appRecord;
@property (nonatomic,retain) NSIndexPath *indexPathInTableView;
@property (nonatomic,assign) id <IconDownloaderDelegate> delegate;

@property (nonatomic,retain) NSMutableData *activeDownload;
@property (nonatomic,retain) NSURLConnection *imageConnection;

- (void)startDownload;
- (void)cancelDownload;

@end

@protocol IconDownloaderDelegate 

- (void)appImageDidLoad:(NSIndexPath *)indexPath;

@end

.m文件-

#import \"IconDownloader.h\"
#import \"MixtapeInfo.h\"

#define kAppIconHeight 48
#define TMP NSTemporaryDirectory()

@implementation IconDownloader

@synthesize appRecord;
@synthesize indexPathInTableView;
@synthesize delegate;
@synthesize activeDownload;
@synthesize imageConnection;

#pragma mark

- (void)dealloc
{
    [appRecord release];
    [indexPathInTableView release];

    [activeDownload release];

    [imageConnection cancel];
    [imageConnection release];

    [super dealloc];
}

- (void)startDownload
{
    self.activeDownload = [NSMutableData data];

    // alloc+init and start an NSURLConnection; release on completion/failure
    NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:
                             [NSURLRequest requestWithURL:
                              [NSURL URLWithString:appRecord.mixtape_image]] delegate:self];
    self.imageConnection = conn;
    [conn release];

}

- (void)cancelDownload
{
    [self.imageConnection cancel];
    self.imageConnection = nil;
    self.activeDownload = nil;
}


#pragma mark -
#pragma mark Download support (NSURLConnectionDelegate)

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [self.activeDownload appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    // Clear the activeDownload property to allow later attempts
    self.activeDownload = nil;

    // Release the connection now that it\'s finished
    self.imageConnection = nil;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{   
    // Set appIcon and clear temporary data/image
    UIImage *image = [[UIImage alloc] initWithData:self.activeDownload];
    self.appRecord.mixtape_image_obj = image;

    self.activeDownload = nil;
    [image release];

    // Release the connection now that it\'s finished
    self.imageConnection = nil;

    // call our delegate and tell it that our icon is ready for display
    [delegate appImageDidLoad:self.indexPathInTableView];
}

@end

这就是我们的用法-

#import \"IconDownloader.h\"

@interface RootViewController : UITableViewController <UIScrollViewDelegate,IconDownloaderDelegate>
{
    NSArray *entries;   // the main data model for our UITableView
    NSMutableDictionary *imageDownloadsInProgress;  // the set of IconDownloader objects for each app
}

在.m文件中-

- (void)startIconDownload:(AppRecord *)appRecord forIndexPath:(NSIndexPath *)indexPath
{
    IconDownloader *iconDownloader = [imageDownloadsInProgress objectForKey:indexPath];
    if (iconDownloader == nil) 
    {
        iconDownloader = [[IconDownloader alloc] init];
        iconDownloader.appRecord = appRecord;
        iconDownloader.indexPathInTableView = indexPath;
        iconDownloader.delegate = self;
        [imageDownloadsInProgress setObject:iconDownloader forKey:indexPath];
        [iconDownloader startDownload];
        [iconDownloader release];   
    }
}

这是代表被自动调用-

// called by our ImageDownloader when an icon is ready to be displayed
- (void)appImageDidLoad:(NSIndexPath *)indexPath
{
    IconDownloader *iconDownloader = [imageDownloadsInProgress objectForKey:indexPath];
    if (iconDownloader != nil)
    {
        UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:iconDownloader.indexPathInTableView];

        // Display the newly loaded image
        cell.imageView.image = iconDownloader.appRecord.appIcon;
    }
}

    ,这是创建自己的委托的基本概念 委托对于在应用程序中手动控制视图控制器数组中的传输非常有用。使用委托，您可以很好地管理控制流。 这是自己的代表的一个小例子。 创建一个协议类...。（仅.h） SampleDelegate.h

#import


@protocol SampleDelegate
@optional

#pragma Home Delegate

-(NSString *)getViewName;

@end

在要作为另一个类的委托的类中，将以上协议类导入。在我前任我正在使用AppDelegate来委托HomeViewController的Object。 还要在Delegate Reference <>中的DelegateName上方添加 ownDelegateAppDelegate.h

#import \"SampleDelegate.h\"

@interface ownDelegateAppDelegate : NSObject <UIApplicationDelegate,SampleDelegate> {

}

ownDelegateAppDelegate.m

//setDelegate of the HomeViewController\'s object as
[homeViewControllerObject setDelegate:self];

//add this delegate method definition
-(NSString *)getViewName
{
    return @\"Delegate Called\";
}

HomeViewController.h

#import
#import \"SampleDelegate.h\"

@interface HomeViewController : UIViewController {

    id<SampleDelegate>delegate;
}

@property(readwrite,assign) id<SampleDelegate>delegate;

@end

HomeViewController.h

- (void)viewDidAppear:(BOOL)animated {

    [super viewDidAppear:animated];


    UILabel *lblTitle = [[UILabel alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    lblTitle.text = [delegate getViewName];
    lblTitle.textAlignment = UITextAlignmentCenter;
    [self.view addSubview:lblTitle];
}