.Net vs Cocoa 字符串格式

Question

我可以重现以下 C#/.NET：

//A
String.Format("There are {0} cats in my {1} and no {2}", 2, "house", "dogs");

在 Objective-C/Cocoa 中：

//B
[NSString stringWithFormat:@"There are %d cats in my %@ and no %@", 2, "house", "dogs"];

但我不能这样做：

//C
String.Format("I have {0} dogs in my house.  My {0} dogs are very nice, but it is hard to walk {0} dogs at the same time.", numDogs);

在 Objective-C 中：

//D
[NSString stringWithFormat:@"I have %d dogs in my house.  My %d dogs are very nice, but it is hard to walk %d dogs at the same time.", numDogs];

因为它使用 printf 格式或其他格式。有没有更高级的方法来做到这一点？有没有办法在字符串解析中做 KVC？

这在技术上是我想要的：

[player setValue:@"Jimmy" forKey@"PlayerName"];
//later
[NSString stringWithMagicFormat:@"<PlayerName> sat on a bench in the middle of winter, and <GenderPronoun> felt very cold." andPlayer:player];
// or
[NSString stringwithMagicFormat: playerEnteredStringWithTagInIt andPlayer:player];

但我会接受：

String.Format(playerEnteredStringWithTagInIt, player.PlayerName, player.PlayerGender, player.GenderPronoun, ...);

谢谢，

Answer 1

[NSString stringWithFormat:@"I have %1$d dogs in my house.  My %1$d dogs are very nice, but it is hard to walk %1$d dogs at the same time.", numDogs];

（见man 3 printf。）

Answer 2

如果您使用的是NSString 和stringWithFormat:，那么我认为C99 合规性并不真正适用：虽然stringWithFormat: 与printf 相似，但它有自己的实现已经存在了一会儿。

NSLocalizedString() 宏实际上会自动为您执行此操作。例如，假设我有以下代码：

 @implementation MDAppController

- (id)init {
    if (self = [super init]) {
        NSArray *catsArray = [NSArray array];
        NSString *string = [NSString stringWithFormat:
         NSLocalizedString(@"There are %lu %@ %@ in my home.", @"no comment"),
        (unsigned long)[catsArray count],
                            NSLocalizedString(@"red", @""),
                            NSLocalizedString(@"cats", @"")];
        NSLog(@"string == %@", string);
    }
    return self;
}

@end

如果我随后在终端中运行以下命令

/usr/bin/genstrings ~/Developer/NSLocalizedString/MDAppController.m -o ~/Desktop/Strings

（虽然我更喜欢将窗口标题栏中的代理图标拖到我保留在 Dock 中的 AppleScript 小滴上：GenerateStrings.app。它（过度）将生成的 .strings 文件写入 ~/Desktop/Strings/（创建如有必要）。您可以通过将脚本拖放到 AppleScript 编辑器来编辑脚本）。

它将生成一个 UTF16 Localizable.strings 文件，您可以将其添加到您的项目中。其中将包含以下内容：

English.lproj/Localizable.strings

/* No comment provided by engineer. */
"cats" = "cats";

/* No comment provided by engineer. */
"red" = "red";

/* no comment */
"There are %lu %@ %@ in my home." = "There are %1$lu %2$@ %3$@ in my home.";

将其复制到西班牙语项目子文件夹并根据需要更改项目的顺序（因为在西班牙语中，形容词通常位于名词之后）：

Spanish.lproj/Localizable.strings

/* No comment provided by engineer. */
"cats" = "gatos";

/* No comment provided by engineer. */
"red" = "rojos";

/* no comment */
"There are %lu %@ %@ in my home." = "Está %1$lu %3$@ %2$@ en mi casa.";

当英语是我在语言和文本首选项窗格中的主要（最顶层）语言时：

1/20/2011 12:59:37 PM NSLocalizedString[1777] string == There are 0 red cats in my home.

当西班牙语是我在语言和文本首选项窗格中的主要（最顶层）语言时：

1/20/2011 12:37:02 PM NSLocalizedString[1702] string == Está 0 gatos rojos en mi casa.

.strings 文件在某种意义上是键值对。

欲了解更多信息，请参阅Resource Programming Guide: String Resources

Answer 3

我喜欢每个人的答案，但我只在 Docs 中花了 15 分钟，就找到了我正在寻找的答案……叹息，RTM！这是我的解决方案，以防其他人正在寻找类似的东西。

// Put this in a category of NSString
- (NSString*) stringByReplacingOccurrencesOfKeysWithValues:(NSDictionary*)keyValuePairs
{
    NSString *fStr = self;
    if (keyValuePairs) {
        for (NSString *key in [keyValuePairs allKeys]) {
            NSString *value = [NSString stringWithFormat:@"%@",[keyValuePairs valueForKey:key]];
            fStr = [fStr stringByReplacingOccurrencesOfString:key withString:value];
        }
    }
    return fStr;
}

似乎工作正常，这是我的测试代码：

// testing NSString+Keys
NSMutableDictionary *mud = [NSMutableDictionary dictionaryWithCapacity:1];
[mud setValue:@"Jimmy" forKey:@"{PlayerName}"];
[mud setValue:[NSNumber numberWithInt:97] forKey:@"{HitPoints}"];
[mud setValue:[NSNumber numberWithFloat:1.0678f] forKey:@"{meters}"];
NSString *mystr = [@"Help me {PlayerName} before it is too late! I only have {HitPoints}hp left!  And I am {meters}m away! {PlayerName} hurry!" stringByReplacingOccurrencesOfKeysWithValues:mud];
NSLog(mystr);

输出是：

在为时已晚之前帮助我吉米！我只剩下97hp了！而我在 1.0678m 之外！吉米快点！