从URL下载文件并保存到iPhone上的资源

Question

是否可以通过以编程方式将文件(即sqlite数据库文件)从Internet下载到您的iPhone应用程序中,以便以后在应用程序中使用？

我正在尝试使用NSURLConnection,但无法保存文件.

这是我正在尝试的示例代码:

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSString *file = [NSString stringWithFormat:@"http://en.wikipedia.org/wiki/Text_file"];
    NSURL *fileURL = [NSURL URLWithString:file];

    NSURLRequest *req = [NSURLRequest requestWithURL:fileURL];
    NSURLConnection *conn = [NSURLConnection connectionWithRequest:req delegate:self];  
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [self.fileData setLength:0];
    self.totalFileSize = [NSNumber numberWithLongLong:[response expectedContentLength]];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
        [self.fileData appendData:data];        
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSArray *dirArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,    NSUserDomainMask, YES);
    NSLog(@"%@", [dirArray objectAtIndex:0]);

    NSString *path = [NSString stringWithFormat:@"%@/blah.text", [dirArray objectAtIndex:0]];

    if ([self.fileData writeToFile:path options:NSAtomicWrite error:nil] == NO) {
        NSLog(@"writeToFile error");
    }
    else {
        NSLog(@"Written!");
    }
}

Answer 1

什么是fileData？它是如何定义和初始化的？

  fileData = [NSMutableData data];

应该在以下某个地方:

NSURLConnection *conn = [NSURLConnection connectionWithRequest:req delegate:self];

您必须初始化fileData并按内存管理规则保留它.

试试我的回答.有用!