Object Storage Service:Prevent overwriting objects that have the same name (iOS SDK)

Usage notes

• Before you use the sample code in this topic, create an OSSClient instance using a custom domain name, Security Token Service (STS), or other methods. For more information, see Initialization (iOS SDK).

Simple upload

The following code shows how to prevent an object with the same name from being overwritten during a simple upload:

OSSPutObjectRequest * put = [OSSPutObjectRequest new];

// Specify the bucket name. Example: examplebucket. For more information about bucket naming conventions, see Bucket naming conventions.
put.bucketName = @"examplebucket";
// Specify the full path of the object. Do not include the bucket name. Example: exampledir/exampleobject.txt. For more information about object naming conventions, see Object naming conventions.
put.objectKey = @"exampledir/exampleobject.txt";
// Specify the full path of the local file to upload.
put.uploadingFileURL = [NSURL fileURLWithPath:@"/storage/emulated/0/oss/examplefile.txt"];

// Specify whether to overwrite an existing object that has the same name.
// If you do not specify x-oss-forbid-overwrite, an existing object that has the same name is overwritten by default.
// If you set x-oss-forbid-overwrite to false, an existing object that has the same name is overwritten.
// If you set x-oss-forbid-overwrite to true, an existing object that has the same name is not overwritten. If an object with the same name already exists, the program reports an error.
put.objectMeta = @{@"x-oss-forbid-overwrite": @"true"};

// Optional. Set the upload progress.
put.uploadProgress = ^(int64_t bytesSent, int64_t totalByteSent, int64_t totalBytesExpectedToSend) {
    // The current number of bytes sent, the total number of bytes sent, and the total number of bytes to send.
    NSLog(@"%lld, %lld, %lld", bytesSent, totalByteSent, totalBytesExpectedToSend);
};
OSSTask * putTask = [client putObject:put];
[putTask continueWithBlock:^id(OSSTask *task) {
    if (!task.error) {
        NSLog(@"upload object success!");
    } else {
        NSLog(@"upload object failed, error: %@" , task.error);
    }
    return nil;
}];
// Block the current thread to wait for the task to complete.
// [putTask waitUntilFinished];

Copying files

The following code shows how to prevent an existing object from being overwritten when you copy an object:

OSSCopyObjectRequest * copy = [OSSCopyObjectRequest new];
// Specify the source bucket name.
copy.sourceBucketName = @"srcbucket";
// Specify the full path of the source object.
copy.sourceObjectKey = @"dir1/srcobject.txt";
// Specify the destination bucket name.
copy.bucketName = @"destbucket";
// Specify the full path of the destination object.
copy.objectKey = @"dir2/destobject.txt";

// Specify whether to overwrite an existing object that has the same name.
// If you do not specify x-oss-forbid-overwrite, an existing object that has the same name is overwritten by default.
// If you set x-oss-forbid-overwrite to false, an existing object that has the same name is overwritten.
// If you set x-oss-forbid-overwrite to true, an existing object that has the same name is not overwritten. If an object with the same name already exists, the program reports an error.
copy.objectMeta = @{@"x-oss-forbid-overwrite": @"true"};

OSSTask * task = [client copyObject:copy];
[task continueWithBlock:^id(OSSTask *task) {
    if (!task.error) {
        NSLog(@"copy object success!");
    } else {
        NSLog(@"copy object failed, error: %@" , task.error);
    }
    return nil;
}];
// Block the current thread to wait for the task to complete.
// [putTask waitUntilFinished];

Multipart upload

The following code shows how to prevent an object with the same name from being overwritten during a multipart upload:

__block NSString * uploadId = nil;
__block NSMutableArray * partInfos = [NSMutableArray new];
// Specify the bucket name. Example: examplebucket.
NSString * uploadToBucket = @"examplebucket";
// Specify the full path of the object. Do not include the bucket name. Example: exampledir/exampleobject.txt.
NSString * uploadObjectkey = @"exampledir/exampleobject.txt";
OSSInitMultipartUploadRequest * init = [OSSInitMultipartUploadRequest new];
init.bucketName = uploadToBucket;
init.objectKey = uploadObjectkey;

// Specify whether to overwrite an existing object that has the same name.
// If you do not specify x-oss-forbid-overwrite, an existing object that has the same name is overwritten by default.
// If you set x-oss-forbid-overwrite to false, an existing object that has the same name is overwritten.
// If you set x-oss-forbid-overwrite to true, an existing object that has the same name is not overwritten. If an object with the same name already exists, the program reports an error.
init.objectMeta = @{@"x-oss-forbid-overwrite": @"true"};
// The response to multipartUploadInit contains an upload ID. The upload ID uniquely identifies the multipart upload task. You can use this upload ID to perform operations, such as canceling or querying the multipart upload task.
OSSTask * initTask = [client multipartUploadInit:init];
[initTask waitUntilFinished];
if (!initTask.error) {
    OSSInitMultipartUploadResult * result = initTask.result;
    uploadId = result.uploadId;
} else {
    NSLog(@"multipart upload failed, error: %@", initTask.error);
    return;
}

// Specify the full path of the local file to upload.
NSString * filePath = @"/storage/emulated/0/oss/examplefile.txt";
// Obtain the size of the file to upload.
uint64_t fileSize = [[[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:nil] fileSize];
// Set the part number. Part numbers start from 1. Each uploaded part has a part number that ranges from 1 to 10,000.
int chuckCount = *;
// Set the part size in bytes. The part size can range from 100 KB to 5 GB.
uint64_t offset = fileSize/chuckCount;
for (int i = 1; i <= chuckCount; i++) {
    OSSUploadPartRequest * uploadPart = [OSSUploadPartRequest new];
    uploadPart.bucketName = uploadToBucket;
    uploadPart.objectkey = uploadObjectkey;
    uploadPart.uploadId = uploadId;
    uploadPart.partNumber = i; // part number start from 1

    NSFileHandle* readHandle = [NSFileHandle fileHandleForReadingAtPath:filePath];
    [readHandle seekToFileOffset:offset * (i -1)];

    NSData* data = [readHandle readDataOfLength:offset];
    uploadPart.uploadPartData = data;

    OSSTask * uploadPartTask = [client uploadPart:uploadPart];

    [uploadPartTask waitUntilFinished];

    if (!uploadPartTask.error) {
        OSSUploadPartResult * result = uploadPartTask.result;
        uint64_t fileSize = [[[NSFileManager defaultManager] attributesOfItemAtPath:uploadPart.uploadPartFileURL.absoluteString error:nil] fileSize];
        [partInfos addObject:[OSSPartInfo partInfoWithPartNum:i eTag:result.eTag size:fileSize]];
    } else {
        NSLog(@"upload part error: %@", uploadPartTask.error);
        return;
    }
}

OSSCompleteMultipartUploadRequest * complete = [OSSCompleteMultipartUploadRequest new];
complete.bucketName = uploadToBucket;
complete.objectKey = uploadObjectkey;
complete.uploadId = uploadId;
complete.partInfos = partInfos;
// Specify whether to overwrite an existing object that has the same name when you complete the multipart upload.
// If you do not specify x-oss-forbid-overwrite, an existing object that has the same name is overwritten by default.
// If you set x-oss-forbid-overwrite to false, an existing object that has the same name is overwritten.
// If you set x-oss-forbid-overwrite to true, an existing object that has the same name is not overwritten. If an object with the same name already exists, the program reports an error.
complete.completeMetaHeader = @{@"x-oss-forbid-overwrite": @"true"};

OSSTask * completeTask = [client completeMultipartUpload:complete];

[[completeTask continueWithBlock:^id(OSSTask *task) {
    if (!task.error) {
        NSLog(@"multipart upload success!");
    } else {
        NSLog(@"multipart upload error: %@", task.error);
    }
    return nil;
}] waitUntilFinished];

References

• For more information about the API operation for simple upload, see PutObject.

• For more information about the API operation for copying an object, see CopyObject.

• A complete multipart upload consists of three API operations. For more information, see the following topics:

  • For more information about the API operation for initiating a multipart upload event, see InitiateMultipartUpload.

  • For more information about the API operation for uploading a part, see UploadPart.

  • For more information about the API operation for completing a multipart upload, see CompleteMultipartUpload.

• For more information about how to initialize an OSSClient instance, see Initialize an OSSClient instance.