11

是否可以通过编程方式从 Internet 将文件（即 sqlite 数据库文件）下载到您的 iPhone 应用程序中以供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!");
    }
}
4

4 回答 4

5

什么是文件数据？它是如何定义和初始化的？

  fileData = [NSMutableData data];

应该在之后的某个地方： 

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

您必须根据内存管理规则初始化 fileData 并保留它。

试试我的回答。有用！

于 2010-01-20T15:18:22.093 回答
4

您需要扩展路径stringByAppendingPathComponent

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"bookdb.sql"];
于 2010-01-20T15:18:50.490 回答
4

在方法中尝试此代码并执行，

NSURL *url=[NSURL URLWithString:@"http://en.wikipedia.org/wiki"];

NSData *dbFile = [[NSData alloc] initWithContentsOfURL:url];   

NSString *resourceDocPath = [[NSString alloc] initWithString:[[[[NSBundle mainBundle]  resourcePath] stringByDeletingLastPathComponent]stringByAppendingPathComponent:@"Documents"]];

NSString *filePath = [resourceDocPath stringByAppendingPathComponent:@"Text_file.txt"];  

[dbFile writeToFile:filePath atomically:YES];
于 2012-07-10T10:49:57.707 回答
0

这可能对您有用。

NSString *stringURL = @"http://www.somewhere.com/thefile.png";
NSURL  *url = [NSURL URLWithString:stringURL];
NSData *urlData = [NSData dataWithContentsOfURL:url];
if ( urlData )
{
  NSArray       *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSString  *documentsDirectory = [paths objectAtIndex:0];  

  NSString  *filePath = [NSString stringWithFormat:@"%@/%@", documentsDirectory,@"filename.png"];
  [urlData writeToFile:filePath automically:YES];
}

请注意，这是一个writeToFile同步方法，因此它会暂停/阻止您的 UI。

于 2015-03-31T21:27:42.843 回答