ios 从 url 下载文件并保存到 iPhone 上的资源
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原文地址: http://stackoverflow.com/questions/2102267/
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Downloading a file from url and saving to resources on iPhone
提问by msk
Is it possible to download a file (i.e. an sqlite database file) from the Internet into your iPhone application programmatically for later use within the application?
是否可以以编程方式从 Internet 下载文件（即 sqlite 数据库文件）到您的 iPhone 应用程序中以供以后在应用程序中使用？
I am trying using NSURLConnection, but not able to save the file.
我正在尝试使用NSURLConnection，但无法保存文件。
Here is the example code I am trying:
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!");
}
}
采纳答案by Jordan
What is fileData? How is it defined and initialized?
什么是文件数据？它是如何定义和初始化的？
fileData = [NSMutableData data];
should be somewhere after:
应该在某处之后：
NSURLConnection *conn = [NSURLConnection connectionWithRequest:req delegate:self];
You have to initialize fileData and retain it per memory management rules.
您必须初始化 fileData 并根据内存管理规则保留它。
Try it with my answer. It Works!
用我的答案试试。有用！
回答by slf
You need to expand the path with stringByAppendingPathComponent
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"];
回答by SURESH SANKE
Try this code in a method and execute,
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];
回答by Ans
This can be useful for you.
这对你很有用。
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];
}
Note that this is a writeToFilemethod is synchronous, so it will halt/block your UI.
请注意，这是一个writeToFile同步方法，因此它会暂停/阻止您的 UI。
