如果NSData<固定大小在可可 [英] How can add more space if NSData < fixed size in Cocoa

问题描述

我有一个问题：我使用以下代码从 NSData 获取数据，但我想从 [0; 2048]字节获取数据。如果我的数据> 2048 * 强文本 *，它可以运行正常，但如果我的数据< 2048 ，它会出错。所以我想添加更多的一些空间，如果我的数据< 2048 到足够的 2048字节。你可以帮我吗？非常感谢。

I have a problem: I used below codes to get data from NSData, but I want to get data from [0;2048] bytes. If my data > 2048*strong text*, it can run fine but if my data < 2048, it'll wrong. So that I want to add more some space at last if my data < 2048 to enough 2048 bytes. Can you help me? Thanks so much.

 NSData *data = [NSData dataWithBytes:[arrayText UTF8String] length:[arrayText lengthOfBytesUsingEncoding:NSUTF8StringEncoding]];
 NSData *datawrite = [data subdataWithRange:NSMakeRange(0, 2048)];

如果 data> 2048字节，如果 data < 2048字节，我的MAC应用程序挂起。请给我任何建议。提前感谢

Above code is work fine if data > 2048 bytes, if data < 2048 bytes , my MAC app hangs. Please give me any suggestion. Thanks in advance

推荐答案

好的，这将从 data 。如果结果是< 2048字节，新数据将填充为2048字节。

Ok, this will copy as many bytes as are available (up to 2048) from data. If the result is < 2048 bytes, the new data will be padded to 2048 bytes.

NSMutableData * datawrite = [ data subdataWithRange:(NSRange){ 0, MIN( 2048, data.length ) } ] mutableCopy ] ;
[ datawrite setLength:2048 ] ;

但是，你能告诉我们更广泛的应用吗？这看起来像一个奇怪的用例，我想了解更多。

BUT: Can you tell us the broader application? This seems like a strange use case and I'd like to understand more.

这篇关于如果NSData&lt;固定大小在可可的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！