Question

所以我对这款iphone开发的东西很新......而且我被卡住了。

我正在构建一个连接到twitter api的应用程序。但是，当调用connectionDidFinishLoading方法时，它似乎无法识别该委托。

以下是请求类的源代码：

#import "OnePageRequest.h"

@implementation OnePageRequest

@synthesize username;
@synthesize password;
@synthesize receivedData;
@synthesize delegate;
@synthesize callback;
@synthesize errorCallBack;
@synthesize contactsArray;

-(void)friends_timeline:(id)requestDelegate requestSelector:(SEL)requestSelector{
    //set the delegate and selector
    self.delegate = requestDelegate;
    self.callback = requestSelector;

    //Set up the URL of the request to send to twitter!!
    NSURL *url = [NSURL URLWithString:@"http://twitter.com/statuses/friends_timeline.xml"];

    [self request:url];
}

-(void)request:(NSURL *) url{

    theRequest = [[NSMutableURLRequest alloc] initWithURL:url];
    theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

    if (theConnection){
        //Create the MSMutableData that will hold the received data.
        //receivedData is declared as a method instance elsewhere
        receivedData=[[NSMutableData data] retain];
    }else{
        //errorMessage.text = @"Error connecting to twitter!!";
    }
}

-(void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge{

    if ([challenge previousFailureCount] == 0){
        NSLog(@"username: %@ ",[self username]);
        NSLog(@"password: %@ ",[self password]);
        NSURLCredential *newCredential = [NSURLCredential credentialWithUser:[self username]
                                                                    password:[self password]
                                                                 persistence:NSURLCredentialPersistenceNone];
        [[challenge sender] useCredential:newCredential forAuthenticationChallenge:challenge];
    } else {
        [[challenge sender] cancelAuthenticationChallenge:challenge];
        NSLog(@"Invalid Username or password!");
    }
}   

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{

    [receivedData setLength:0];

}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{

    [receivedData appendData:data];

}

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{

    [theConnection release];
    [receivedData release];
    [theRequest release];

    NSLog(@"Connection failed. Error: %@ %@", [error localizedDescription], [[error userInfo] objectForKey:NSErrorFailingURLStringKey]);

    if(errorCallBack){
        [delegate performSelector:errorCallBack withObject:error];
    }
}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection{

    if (delegate && callback){
        if([delegate respondsToSelector:[self callback]]){
            [delegate performSelector:[self callback] withObject:receivedData];
        }else{
            NSLog(@"No response from delegate!");
        }
    }
    [theConnection release];
    [theRequest release];
    [receivedData release];
}

这是.h：

@interface OnePageRequest : NSObject {

    NSString *username;
    NSString *password;
    NSMutableData *receivedData;
    NSURLRequest *theRequest;
    NSURLConnection *theConnection;
    id  delegate;
    SEL callback;
    SEL errorCallBack;
    NSMutableArray *contactsArray;
}

@property (nonatomic,retain) NSString *username;
@property (nonatomic,retain) NSString *password;
@property (nonatomic,retain) NSMutableData *receivedData;
@property (nonatomic,retain) id delegate;
@property (nonatomic) SEL   callback;
@property (nonatomic) SEL   errorCallBack;
@property (nonatomic,retain) NSMutableArray *contactsArray;

-(void)friends_timeline:(id)requestDelegate requestSelector:(SEL)requestSelector;
-(void)request:(NSURL *) url;

@end

在方法：connectionDidFinishLoading中，以下内容永远不会执行：

[delegate performSelector:[self callback] withObject:receivedData];

相反，我收到消息：“没有来自代表的回应”

任何人都能看到我做错了什么？！或者可能导致问题的原因是什么？

Answer 1

[delegate performSelector:[self callback] withObject:receivedData];

（抱歉，我对SEL论点的评论是由于阅读粘贴到问题中的代码有困难。）

使用connectionDidFinishLoading:中的调试器可以验证delegate和callback变量是否为零？

检索回调它具有值friends_timeline_callback，这是我期望的

下一步是验证选择器实际上是否正确。即如果回调方法有一个参数，它应该是@selector(friends_timeline_callback:)（注意尾随:字符，以指定参数是方法签名的一部分）

iPhone应用程序：委托没有回应

1 个答案: