iphone - 如何让 NSURLConnection 委托(delegate)方法触发？

Question

当我加载与此类关联的 View 时，我似乎无法调用委托(delegate)方法。它们都没有触发。我敢肯定这是我忽略的事情，但我终生无法弄清楚原因。

下载更新.h

#import <UIKit/UIKit.h>

@interface DownloadUpdates : UIViewController

    @property (strong, nonatomic) NSMutableData *responseData;
    @property (strong, nonatomic) NSURLConnection *connection;

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

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

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

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

@end

下载更新.m

出于保护隐私的目的，该 URL 已被删除，但它只是调用将返回 JSON 数据的 API。此 URL 按预期运行，因此它是代码问题。

#import "DownloadUpdates.h"

@interface DownloadUpdates ()

@end

@implementation DownloadUpdates

- (void)connection:(NSURLConnection *)_connection didReceiveResponse:(NSURLResponse *)response
{
    _responseData = [[NSMutableData alloc] init];
    NSLog(@"Response received");
}

- (void)connection:(NSURLConnection *)_connection didReceiveData:(NSData *)data
{
    [_responseData appendData:data];
        NSLog(@"Data received");
}

- (void)connection:(NSURLConnection *)_connection didFailWithError:(NSError *)error
{
    NSLog(@"Unable to fetch data");
}

- (void)connectionDidFinishLoading:(NSURLConnection *)_connection
{
    NSLog(@"Succeeded! Received %d bytes of data",[_responseData
                                                   length]);
//    NSString *txt = [[NSString alloc] initWithData:_responseData encoding: NSASCIIStringEncoding];
}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSURL *myURL = [NSURL URLWithString:@"URL HERE"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:myURL cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60];

    _connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
    // Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

如果您能提供任何帮助/建议，我将不胜感激。

Answer 1

使用属性应用强修饰符:

self.responsedata = [[NSMutableData alloc] init];
(.....)
self.connection = [[NSURLConnection alloc] initWithRequest: ....etc...