How to download a specific range of data by using OSS SDK for iOS - Object Storage Service

You can perform range download to download a specific range of data of an object.

Usage notes

Before you run the sample code in this topic, you must create an OSSClient instance by using methods such as using a custom domain name or Security Token Service (STS). For more information, see Initialization.
Note
The region of the bucket is determined by the region of the endpoint specified for initialization.
To download an object, you must have the ossGetObject permission. For more information, see Attach a custom policy to a RAM user.

Range download is suitable for downloading large objects. If the Range parameter is specified in the request header, the response contains the length of the entire object and the range returned in this response.

Examples

The following sample code provides an example on how to perform range download:

OSSGetObjectRequest * request = [OSSGetObjectRequest new];
// Specify the name of the bucket. Example: examplebucket. 
request.bucketName = @"examplebucket";
// Specify the full path of the object. Do not include the bucket name in the full path. Example: exampledir/exampleobject.txt. 
request.objectKey = @"exampledir/exampleobject.txt";
request.range = [[OSSRange alloc] initWithStart:1 withEnd:99]; // bytes=1-99
// request.range = [[OSSRange alloc] initWithStart:-1 withEnd:99]; // bytes=-99
// request.range = [[OSSRange alloc] initWithStart:10 withEnd:-1]; // bytes=10-
request.downloadProgress = ^(int64_t bytesWritten, int64_t totalBytesWritten, int64_t totalBytesExpectedToWrite) {
    NSLog(@"%lld, %lld, %lld", bytesWritten, totalBytesWritten, totalBytesExpectedToWrite);
};
OSSTask * getTask = [client getObject:request];
[getTask continueWithBlock:^id(OSSTask *task) {
    if (!task.error) {
        NSLog(@"download object success!");
        OSSGetObjectResult * getResult = task.result;
        NSLog(@"download result: %@", getResult.downloadedData);
    } else {
        NSLog(@"download object failed, error: %@" ,task.error);
    }
    return nil;
}];
// [getTask waitUntilFinished];
// [request cancel];

References

For more information about the API operation that you can call to perform range download, see GetObject.
For more information about how to initialize an OSSClient instance, see Initialization.