如何在Objective-C中从服务器下载CSV文件

Question

我正在开发一个新的iPhone应用程序,在这里,我已经从本地解析了一个'csv'文件,并与我一起工作.当我尝试以编程方式从服务器下载'csv'文件时,它没有为我锻炼.请你帮助我好吗？

从本地文件加载数据(工作正常)

- (void)viewDidLoad
{  
    [super viewDidLoad];

    NSString * file = [[NSBundle bundleForClass:[self class]] pathForResource:@"sample" ofType:@"csv"];

    NSStringEncoding encoding = 0;
    NSString * csv = [NSString stringWithContentsOfFile:file usedEncoding:&encoding error:nil];
    NSArray *fields = [csv CSVComponents];
    NSLog(@"fields: %@", fields); //getting the result content 
}

从服务器下载文件(失败)

-(void) connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"connectionDidFinishLoading"); //nothing showing here

    NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *fullName = [NSString stringWithFormat:@"quotes.csv"];

    NSString *fullFilePath = [NSString stringWithFormat:@"%@/%@",docDir,fullName];
    [receivedData writeToFile:fullFilePath atomically:YES];
} 

-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    NSLog(@"data: %@", data); //nothing showing here

    if (receivedData)
        [receivedData appendData:data];
    else 
        receivedData = [[NSMutableData alloc] initWithData:data];
}

- (void)loadDatafromURL
{    
    NSURL *url = [NSURL URLWithString:@"http://download.finance.yahoo.com/d/quotes.csv?s=^GSPC,^IXIC,^dji,^GSPC,^BVSP,^GSPTSE,^FTSE,^GDAXI,^FCHI,^STOXX50E,^AEX,^IBEX,^SSMI,^N225,^AXJO,^HSI,^NSEI&f=sl1d1t1c1ohgv&e=.csv"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [NSURLConnection connectionWithRequest:request delegate:self];
}

Answer 1

实现此方法:

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

你会发现你得到的错误

Error Domain=NSURLErrorDomain Code=-1000 "bad URL" UserInfo=0xf663f40 {NSUnderlyingError=0xf663de0 "bad URL", NSLocalizedDescription=bad URL}

我之前考虑过以这种方式下载信息,我认为你遇到的一个问题是必须用"+"分隔单独的符号.此外,在提取索引时,您不能将"^"符号作为URL的一部分传递.您必须将其替换为"%5E".

所以,添加这个:

- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"%@", [error description]);
}

并将您的网址更改为:

NSString *urlString = @"http://download.finance.yahoo.com/d/quotes.csv?s=^GSPC+^IXIC+^dji+^GSPC+^BVSP+^GSPTSE+^FTSE+^GDAXI+^FCHI+^STOXX50E+^AEX+^IBEX+^SSMI+^N225+^AXJO+^HSI+^NSEI&f=sl1d1t1c1ohgv&e=.csv";
NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]];

现在它适合我!我甚至检查了输出.csv文件,它看起来不错!每行一个完整的报价.