我刚开始学习Objective-C编程,请包容我,如果这是一个简单的问题,请帮助解答。
我的头文件:
#import <Cocoa/Cocoa.h>
@interface AppDelegate : NSObject <NSApplicationDelegate>
@property (assign) IBOutlet NSWindow *window;
@end
我的实现文件:
#import "AppDelegate.h"
@implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
// Insert code here to initialize your application
// Listing 2-1 Creating a connection using NSURLConnection
// 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.
}
}
@end
在实现文件中的receivedData
未声明。如果在.h文件中声明该变量,则会显示不能在@interface和协议内部声明变量