macOS 10.13：“不再支持调度NSURLDownload加载器。”

Question

在macOS 10.13中运行我的macOS应用程序，我看到打印到控制台：

Scheduling the NSURLDownload loader is no longer supported.

这是什么意思？

Answer 1

在我发现的实例中，Sparkle Updater似乎是罪魁祸首。我猜Sparkle开发团队会关注它，希望在Sparkle更新后我们不会再看到这条消息。

Answer 2

这似乎意味着您刚刚创建了一个已弃用的类NSURLDownload的实例。

为了显示这一点，在Xcode中创建一个新的Cocoa命令行工具项目，并将main.m中的代码替换为以下代码：

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSURL* url = [[NSURL alloc] initWithString:@"https://example.com"];
        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url                                                                        
                                                               cachePolicy:NSURLRequestReloadIgnoringCacheData
                                                           timeoutInterval:30.0];
        NSLog(@"Will print strange sentence to console") ;
        [[NSURLDownload alloc] initWithRequest:request
                                      delegate:nil];
        NSLog(@"Did print strange sentence to console") ;
    }
    return 0;
}

构建并运行。我在控制台中得到了以下结果(去掉时间戳)：

Will print strange sentence to console:
Scheduling the NSURLDownload loader is no longer supported.
Did print strange sentence to console

我要说的是，“修复”是用NSURLSession替换过时的NSURLDownload。

Answer 3

您可以直接在Sparkle的源代码中对其进行更正。通过将NSURLDownload替换为以下内容来更新第82行的SUAppcast.m文件：

NSURLSessionDownloadTask *downloadTask = [[NSURLSession sharedSession] downloadTaskWithRequest:request completionHandler:^(NSURL *location, __unused NSURLResponse *response, NSError *error) {

    if (location) {
        NSString *destinationFilename = NSTemporaryDirectory();
        if (destinationFilename) {
            // The file will not persist if not moved, Sparkle will remove it later. 
            destinationFilename = [destinationFilename stringByAppendingPathComponent:@"Appcast.xml"];

            NSFileManager *fileManager = [NSFileManager defaultManager];
            NSError *anError = nil;
            NSString *fromPath = [location path];
            if ([fileManager fileExistsAtPath:destinationFilename])
                [fileManager removeItemAtPath:destinationFilename error:&anError];
            BOOL fileCopied = [fileManager moveItemAtPath:fromPath toPath:destinationFilename error:&anError];
            if (fileCopied == NO) {
                [self reportError:anError];
            } else {
                self.downloadFilename = destinationFilename;

                dispatch_async(dispatch_get_main_queue(), ^{
                    [self downloadDidFinish:[[NSURLDownload alloc] init]];
                });
            }
        }
    } else {
            [self reportError:error];
    }
 }];

[downloadTask resume];