将 NSData 分成三个块 - 以我开始的更多字节结束

Question

我有一个具有视频上传功能的 iOS 应用程序。我需要将视频数据上传到具有非常特定上传要求的服务器：最大文件大小 15 MB，并且文件上传必须通过不超过 5 MB 的块上传。

我正在使用 subdataWithRange 将视频文件分成三个 NSData 块。这样，无论文件总大小如何，文件块都不会超过 5 MB。我将 NSData 对象分成三个块并检查了大小，结果发现我以开始时的 MORE 字节结束。我知道我是个特别笨的人。

这是我的代码：

// Get the video data object.
NSData *postData = [self getAttachmentData];
    
// Get the file size in bytes.
NSUInteger fileSizeBytes = [postData length];
    
// Split the video into three chunks.
NSData *chunkOne = [postData subdataWithRange:NSMakeRange(0, (fileSizeBytes / 3))];
NSData *chunkTwo = [postData subdataWithRange:NSMakeRange([chunkOne length], ((fileSizeBytes / 3) * 2))];
NSData *chunkThree = [postData subdataWithRange:NSMakeRange([chunkTwo length], (fileSizeBytes - [chunkTwo length]))];
         
NSLog(@"fileSizeBytes: %lu", (unsigned long)fileSizeBytes);
NSLog(@"\n\n");
NSLog(@"chunckOne: %lu", (unsigned long)[chunkOne length]);
NSLog(@"chunckTwo: %lu", (unsigned long)[chunkTwo length]);
NSLog(@"chunckThree: %lu", (unsigned long)[chunkThree length]);
NSLog(@"\n\n");
NSLog(@"chunkTotal: %lu", ((unsigned long)[chunkOne length] + (unsigned long)[chunkTwo length] + (unsigned long)[chunkThree length]));

这是输出日志：

fileSizeBytes: 2132995
 
chunckOne: 710998
chunckTwo: 1421996
chunckThree: 710999

chunkTotal: 2843993

那我做错了什么？我相信我已经正确设置了范围，因此对象被分为三个块。

Answer 1

范围是（开始，长度）而不是（开始，结束）。你做： (0, 710998), (710998, 1421996), (1421996, 710999)。它应该是：(0, 710998), (710998, 710998) 和 (1421996, 710999)

NSUInteger chunkSizeBytes = (fileSizeBytes / 3)
NSData *chunkOne = [postData subdataWithRange:NSMakeRange(0, chunkSizeBytes)];
NSData *chunkTwo = [postData subdataWithRange:NSMakeRange(chunkSizeBytes, chunkSizeBytes)];
NSData *chunkThree = [postData subdataWithRange:NSMakeRange(chunkSizeBytes * 2, fileSizeBytes - (chunkSizeBytes * 2))];

将 NSData 分成三个块 - 以我开始的更多字节结束

Split NSData into three chunks - Ending up with MORE bytes that I started with

byte

objective-c

nsdata

nsuinteger

nsrange