ios - 子类化 NSURLConnection 给出错误 : unrecognized selector sent to instance

Question

我正在尝试创建 NSURLConnection 的子类，其中我有一个附加属性(在本例中为“connectionName”)以帮助我区分 2 个不同的连接。

我创建了子类，将其命名为 CustomURLConnection 并赋予其属性“connectionName”。

然后在我的文件 ImagesViewController.m(这是一个 UICollectionView)中，我导入 header CustomURLConnection 并尝试为连接命名并在之后检索它，但是它不起作用，一旦我进入此 Collection View ，应用程序就会崩溃并出现以下错误:

-[NSURLConnection setConnectionName:]: 无法识别的选择器发送到实例 0x1090a40f0

这是一些代码:(如果你愿意，这里是 CLEARER IMAGE )

CustomURLConnection.h

#import <Foundation/Foundation.h>

@interface CustomURLConnection : NSURLConnection

@property (strong, nonatomic) NSString *connectionName;

@end

ImagesViewController.h

#import <UIKit/UIKit.h>

@interface ImagesViewController : UICollectionViewController<NSURLConnectionDelegate>

@property (strong, nonatomic) UIImageView *imageView;

@end

ImagesViewController.m

...
#import "CustomURLConnection.h"

@interface ImagesViewController (){
    NSArray *contentStrings;
    NSMutableData *contentData; // Holds data from the initial load
    NSMutableData *contentImageData; // Holds data when the user scrolls up/down in the collection view
}
@end

...

-(void)loadInitialData{ // Loads data from page
    NSString *hostStr = @"http://www.website.com/example";
    NSURL *dataURL = [NSURL URLWithString:hostStr];
    NSURLRequest *request = [NSURLRequest requestWithURL:dataURL];
    CustomURLConnection *connectionData = (CustomURLConnection *)[NSURLConnection connectionWithRequest:request delegate:self]; // Make connection
    connectionData.connectionName = @"InitialData"; // Give it a name
}

...

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    // Do some stuff

    NSString *hostStr = @"http://www.website.com/example2";

    _imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0,0,100,100)];
    [imageCell addSubview:_imageView]; // Adds an image view to each collection cell

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:hostStr]];
    CustomURLConnection *connectionImg = (CustomURLConnection *)[NSURLConnection connectionWithRequest:request delegate:self]; // Make connection
    connectionImg.connectionName = @"ImageData"; // Give it a different name than before

    // Do some stuff
    return imageCell;
}

...

// Here are the main methods for the connections
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
    if([((CustomURLConnection *)connection).connectionName isEqualToString:@"InitialData"]){
        contentData = [[NSMutableData alloc] init];
    }
    else{
        contentImageData = [[NSMutableData alloc] init];
    }
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    if([((CustomURLConnection *)connection).connectionName isEqualToString:@"InitialData"]){
        [contentData appendData:data];
    }
    else{
        [contentImageData appendData:data];
    }
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
    if([((CustomURLConnection *)connection).connectionName isEqualToString:@"InitialData"]){
        // Do some stuff
    }
    else{
        UIImage *image = [[UIImage alloc] initWithData:contentImageData];
        _imageView.image = image;
    }
}

我错过了什么吗？我以前多次遇到过这个错误，但原因从来都不相同，这次我似乎无法自己找到解决方案。

希望你能看到我做错了什么并帮助我:)谢谢。

编辑:原来有更好的方法来实现我的目标，have a look here
再次感谢大家的帮助:)

Answer 1

CustomURLConnection *connectionImg = (CustomURLConnection *)[NSURLConnection connectionWithRequest:request delegate:self]; // Make connection

创建一个 NSURLConnection 对象。转换为 CustomURLConnection 不会改变这个对象的类。将该行替换为

CustomURLConnection *connectionImg = [CustomURLConnection connectionWithRequest:request delegate:self]; // Make connection

创建子类的实例。