2

我有这些处理下载的方法

但是初始化NSMutableData的时候出现错误

NSNumber *filesize;
NSMutableData *data;

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    filesize = [NSNumber numberWithUnsignedInteger:[response expectedContentLength]];

}

- (void)connection:(NSURLConnection *)theConnection didReceiveData:(NSData *)recievedData {


    if (data==nil) {
        data =  [[NSMutableData alloc] initWithCapacity:[filesize floatValue]];
    }


    [data appendData:recievedData];
    NSNumber *resourceLength = [NSNumber numberWithUnsignedInteger:[data length]]; //MAGIC
    float progress = [resourceLength floatValue] / [filesize floatValue];
    progressBar.progress = progress;



}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{

    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error "
                                                        message:@" " delegate:self cancelButtonTitle: @"OK"
                                              otherButtonTitles:nil];
    [alertView show];

    connection1=nil;
    [connection1 cancel];



}

- (void)connectionDidFinishLoading:(NSURLConnection*)theConnection {

}

这里产生错误

数据 = [[NSMutableData alloc] initWithCapacity:[filesize floatValue]];

[NSConcreteMutableData initWithCapacity:]：荒谬容量：4294967295，最大大小：2147483648字节'

4

1 回答 1

3

如果NSURLResponse expectedContentLength不知道长度，它将返回 -1（文档说NSURLResponseUnknownLength，这是一个初始化为 -1 的常量）。

然后，您使用一种有趣的方式从long long(result type of NSURLResponse expectedContentLength) via NSNumber numberWithUnsignedIntegerand NSNumber floatValueto NSUInteger(argument to NSMutableData initWithCapacity:)。结果是 -1（内部表示为 0xffffffff）最终为 4294967295（内部也表示为 0xffffffff）。

在这种情况下，您必须测试NSURLResponseUnknownLength并使用不同的初始容量。并且不要使用NSNumber. 如果在合理范围内，只需将有符号long long转换为无符号即可。NSUInteger

于 2013-08-21T19:10:56.777 回答