Swift 读取 plist 并处理错误

Question

我正在尝试创建一个函数，它将 return 一个包含我的 plist 路径的字符串并处理一些错误，例如 fileDoesntExist、notPlistFile、invalidConfiguration。 plist 在启动时作为参数被调用

--配置“${PROJECT_DIR}/configuration.plist”

我创建了一个带有错误的枚举：

enum PathError: Error {
    case fileDoesntExist, notPlistFile, invalidConfiguration
}

我目前的功能是这样的：

func getConfigurationFilePath() throws  -> String  {
    CommandLine.arguments
    
    if let indexPath = CommandLine.arguments.firstIndex(where: {[=12=] == "--configuration"}) {
        let url = URL(fileURLWithPath: CommandLine.arguments[indexPath + 1])
        let data =  try! Data(contentsOf: url)
        
        let pListObject = try PropertyListSerialization.propertyList(from: data, options:PropertyListSerialization.ReadOptions(), format:nil)
        let pListDict = pListObject as? Dictionary<String, AnyObject>
    }

我的plist：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>OutputFile</key>
    <string>/tmp/assessment_output.txt</string>
    <key>ErrorFile</key>
    <string>/tmp/assessment_error.txt</string>
    <key>RunConfiguration</key>
    <dict>
        <key>RunInterval</key>
        <integer>30</integer>
        <key>Iterations</key>
        <string>3</string>
    </dict>
</dict>
</plist>

现在我很难弄清楚如何将这些错误插入到函数中。任何 tips/suggestions?

Answer 1

如果你想抛出自定义错误而不是真正的错误你必须guard所有可能失败的行

enum PathError: Error {
    case invalidParameter, fileDoesntExist, notPlistFile, invalidConfiguration
}

func getConfigurationFilePath() throws  -> String  {
    
    let args = CommandLine.arguments
    guard let indexPath = args.firstIndex(where: {[=10=] == "--configuration"}),
          indexPath + 1 < args.count else {
        throw PathError.invalidParameter
    }
    let url = URL(fileURLWithPath: args[indexPath + 1])
    guard let data = try? Data(contentsOf: url) else {
        throw PathError.fileDoesntExist
    }
    guard let pListObject = try? PropertyListSerialization.propertyList(from: data, format: nil) else {
        throw PathError.notPlistFile
    }
    guard let _ = pListObject as? Dictionary<String, Any> else {
        throw PathError.invalidConfiguration
    }
    return url.path
}

Swift 读取 plist 并处理错误

Swift Reading plist and handle errors

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