objective-c - 使用未声明的标识符

Question

我是 Objective-C 编码新手，请耐心询问这是不是一个简单的问题我的头文件:

#import <Cocoa/Cocoa.h>

@interface AppDelegate : NSObject <NSApplicationDelegate>

@property (assign) IBOutlet NSWindow *window;

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification;
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse*) response;

@end

我的实现文件:

#import "AppDelegate.h"

@implementation AppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    // Insert code here to initialize your application
    NSMutableData *receivedData  =[NSMutableData dataWithCapacity: 0];

    // Create the request
    NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.apple.com/"] cachePolicy:NSURLRequestUseProtocolCachePolicy
                                      timeoutInterval:60.0];

    // Create the NSMutableData to hold the received data.
    // receivedData is an instance variable declared elsewhere.                  
    receivedData = [NSMutableData dataWithCapacity: 0];

    // create the connection with the request
    // and start loading the data
    NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
    if (!theConnection) {
        // Release the receivedData object.
        receivedData = nil;
        // Inform the user that the connection failed.
     }
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSMutableData *receivedData =[NSMutableData dataWithCapacity:0];


    // This method is called when the server has determined that it
    // has enough information to create the NSURLResponse object.

    // It can be called multiple times, for example in the case of a
    // redirect, so each time we reset the data.

    // receivedData is an instance variable declared elsewhere.
    [receivedData setLength:0];
}
@end

当我在实现 appDelegate 中运行代码时，它会发出警告

Method definition for connection:didRecieveResponse :not found

在哪里

-(void)connection line it gives "use of undelcared identifier connection did u mean Collection".

Answer 1

您不需要声明该方法

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

如果您在代码中使用 NSURLConnectionDataDelegate 协议(protocol)，则在头文件中。只需在实现中添加协议(protocol)并使用该协议(protocol)中的方法即可。