视频截帧功能可以从视频流中截取指定时刻的单帧画面，并按指定大小缩放成图片。
以下代码展示如何截取第 1000ms 的视频帧，并将截取后的图片下载到本地。
// 从STS服务获取的临时访问密钥和安全令牌（AccessKey、SecretKey、SecurityToken）
TOSCredential *credential = [[TOSCredential alloc] initWithAccessKey:@"accesskey" secretKey:@"secretkey" securityToken:@"securityToken"];
TOSEndpoint *tosEndpoint = [[TOSEndpoint alloc] initWithURLString:@"endpoint" withRegion:@"region"];
TOSClientConfiguration *config = [[TOSClientConfiguration alloc] initWithEndpoint:tosEndpoint credential:credential];
TOSClient *client = [[TOSClient alloc] initWithConfiguration:config];
TOSGetObjectToFileInput *get = [TOSGetObjectToFileInput new];
get.tosBucket = @"bucket-name";
get.tosKey = @"video-name";
get.tosFilePath = @"your_local_file_path";
get.tosProcess = @"video/snapshot,t_1000";
TOSTask *task = [client getObjectToFile:get];
[task continueWithBlock:^id _Nullable(TOSTask * _Nonnull t) {
if (!t.error) {
NSLog(@"Get object to file success.");
} else {
NSLog(@"Get object to file failed, error: %@" ,t.error);
}
return nil;
}];
关于视频截帧的详细介绍，请参见视频截帧。