ios - MSMessage url 在将其设置为文件的 url 后保持为 nil

Question

我有一个带有 iOS 10 iMessage 应用程序的应用程序。当我将我的文件 URL 附加到 MSMessage 时，message.URL 是 (null)。我真的不知道是什么原因造成的。当我检查日志时，我看到一个正确的 url:URL: file:///thisuser/... 等。但是，message.URL 日志 (空)。

我构建了一个 Exporter 类，它将文件保存到磁盘，然后返回它的路径。

+ (NSString *) saveToDisk:(NSDictionary *)dictionary {
    // Figure out destination name (in public docs dir)
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *zippedName = [self getExportFileName:dictionary withExtension:YES];
    NSString *zippedPath = [documentsDirectory stringByAppendingPathComponent:zippedName];

    // Export to data buffer
    NSData *gzData = [NSKeyedArchiver archivedDataWithRootObject:dictionary];

    if (gzData == nil) return FALSE;

    // Write to disk
    [gzData writeToFile:zippedPath atomically:YES];

    return zippedPath;
}

这将返回如下内容:/Users/thisuses/Library/Developer/CoreSimulator/Devices/.../Documents/new-save.rst，其中 .rst 是专为我的应用程序定制的文件扩展名。这又被添加到 MSMessage。

MSConversation *conversation = [self activeConversation];

MSMessageTemplateLayout *layout = [[MSMessageTemplateLayout alloc] init];
layout.image = [UIImage imageNamed:@"test"];
layout.caption = url.host;

MSMessage *message = [[MSMessage alloc] init];
message.layout = layout;

NSLog(@"Converter: %@", [Converter toDictionary:array]);
NSLog(@"Exporter: %@", [Exporter saveToDisk:[Converter toDictionary:array]]);
NSLog(@"URL: %@", [NSURL fileURLWithPath:[Exporter saveToDisk:[Converter toDictionary:array]]]);

message.URL = [NSURL fileURLWithPath:[Exporter saveToDisk:[Converter toDictionary:array]]];

NSLog(@"Message URL 1: %@", message.URL);

[conversation insertMessage:message completionHandler:^(NSError * error) {
    NSLog(@"MSConvo error: %@",error);
}];

== 编辑:我在代码中添加了检查以查看 Exporter 是否返回了有效的文件路径，结果确实如此。

NSURL *fileURL = [NSURL fileURLWithPath:[Exporter saveRequestToDisk:[Converter databaseToRequest:history]]];

if ([fileURL isFileURL]) {
    NSLog(@"is File URL!");
    message.URL = fileURL;
}

Answer 1

查看 docs 后和略读this article ，我认为 url 属性不应该指向文件。相反，它应该

[...][encode] data to be transmitted with the message.

我想正确的做法是

Encode your application’s data in the URL. For example, you can encode data as key-value pairs in the URL’s query string, as shown below:

guard let components = NSURLComponents(string: myBaseURL) else {
    fatalError("Invalid base url")
}

let size = NSURLQueryItem(name: "Size", value: "Large")
let count = NSURLQueryItem(name: "Topping_Count", value: "2")
let cheese = NSURLQueryItem(name: "Topping_0", value: "Cheese")
let pepperoni = NSURLQueryItem(name: "Topping_1", value: "Pepperoni")
components.queryItems = [size, count, cheese, pepperoni]

guard let url = components.url  else {
    fatalError("Invalid URL components.")
}

message.url = url

(代码取自文档，您可能希望将其转换为 ObjC...)

因此，与其将字典转换为 NSData 并将其写入文件，不如将其编码为 queryItems，可能如下所示:

NSMutableArray *queryItems = [[NSMutableArray alloc] init]; // Or initWithCapacity for the sake of performance...
NSDictionary *dict = [Converter toDictionary:array];

for (id key in dict) {
    id value = queryDictionary[key];
    NSURLQueryItem *queryItem = [NSURLQueryItem queryItemWithName:key value:value];
    [queryItems addObject:queryItem];
}

[url setQueryItems:queryItems];