Swift中for-in循环失效排查：错误处理致仅打印首个尝试值

阿华AIGC实验室

2026-5-8

问题分析与修复方案

Hey there! I see exactly what's going on here—your loop stops after the first password attempt because of how you're handling errors. Let's break down the issues and fix them step by step.

核心问题

错误抛出时机过早：在你的OpenSafe函数里，只要第一个尝试的密码不匹配，你立刻抛出SafeError.wrongCode。一旦抛出错误，函数会立即终止执行，后面的循环迭代根本没机会运行，这就是为什么只打印第一个密码。
尝试次数检查逻辑位置错误：你把guard triedCodes.count <= maximumTries放在了循环结束后，这意味着即使传入的密码数组长度超过了最大尝试次数，代码还是会先遍历完所有密码（如果没提前抛错的话），这显然不符合逻辑。
找到正确密码后未终止流程：就算某次尝试的密码正确，你的代码会继续循环尝试剩下的密码，而不是直接打开保险箱并结束流程。

修复后的代码

enum SafeError: Error { 
    case wrongCode 
    case tooMuchTries 
    case safeIsOpen 
}

struct Safe {
    var safeIsclosed: Bool
    var code: String
    var maximumTries: Int
    
    mutating func openSafe(triedCodes: [String]) throws {
        // 先检查保险箱是否已经打开
        guard safeIsclosed else { throw SafeError.safeIsOpen }
        // 先检查尝试次数是否超过最大值
        guard triedCodes.count <= maximumTries else { throw SafeError.tooMuchTries }
        
        for triedCode in triedCodes {
            print("Try \(triedCode)")
            // 如果密码正确，打开保险箱并终止函数
            if triedCode == code {
                safeIsclosed = false
                print("Password was correct")
                return
            }
        }
        // 所有尝试都失败，抛出错误
        throw SafeError.wrongCode
    }
}

var safe = Safe(safeIsclosed: true, code: "WD1146", maximumTries: 5)
do {
    try safe.openSafe(triedCodes: ["DD377789", "123456", "WD1146", "112378AADD", "DDFG4567"])
} catch SafeError.safeIsOpen {
    print("Safe is already open")
} catch SafeError.tooMuchTries {
    print("You've exceeded the maximum number of allowed tries")
} catch SafeError.wrongCode {
    print("Wrong Password - all attempts failed")
} catch {
    print("Unexpected error: \(error)")
}