我在iOS应用程序的设备上使用userId将keychain作为令牌保存。此功能适用于iPhone 5s / 6/6 Plus，但不适用于iPhone 4s / 5和iPad。在陈述我的应用程序时，我使用userId检查钥匙串中是否存在func tokenExists()。但是然后我得到一个错误：
fatal error: unexpectedly found nil while unwrapping an Optional value
如此处所示：
这是我的钥匙串类，用于保存，加载和删除令牌并检查令牌是否存在：
import UIKit
import Security
// Identifiers
let userAccount:String = "userAccount"
class KeychainService: NSObject {
/*
save token to keychain
*/
func deleteToken() {
self.delete("userId")
}
/*
save token to keychain
*/
func saveToken(token: NSString) {
self.save("userId", data: token)
}
/*
load keychain token
*/
func loadToken() -> NSString? {
var token: AnyObject? = self.load("userId")
return token as? NSString
}
func tokenExists() -> Bool {
let token:NSString = loadToken()!
if (token == "") {
return false
}
else {
return true
}
}
private func delete(service: NSString) {
//var dataFromString: NSData = data.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!
// Instantiate a new default keychain query
var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPassword, service, userAccount], forKeys: [kSecClass, kSecAttrService, kSecAttrAccount])
// Delete any existing items
SecItemDelete(keychainQuery as CFDictionaryRef)
// Check that it worked ok
//println("Token deleted")
}
private func save(service: NSString, data: NSString) {
var dataFromString: NSData = data.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)!
// Instantiate a new default keychain query
var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPassword, service, userAccount, dataFromString], forKeys: [kSecClass, kSecAttrService, kSecAttrAccount, kSecValueData])
// Delete any existing items
SecItemDelete(keychainQuery as CFDictionaryRef)
// Add the new keychain item
var status: OSStatus = SecItemAdd(keychainQuery as CFDictionaryRef, nil)
// Check that it worked ok
//println("Saving status code is: \(status)")
}
private func load(service: NSString) -> AnyObject? {
// Instantiate a new default keychain query
// Tell the query to return a result
// Limit our results to one item
var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPassword, service, userAccount, kCFBooleanTrue, kSecMatchLimitOne], forKeys: [kSecClass, kSecAttrService, kSecAttrAccount, kSecReturnData, kSecMatchLimit])
// I'm not too sure what's happening here...
var dataTypeRef :Unmanaged<AnyObject>?
// Search for the keychain items
let status: OSStatus = SecItemCopyMatching(keychainQuery, &dataTypeRef)
//println("Loading status code is: \(status)")
// I'm not too sure what's happening here...
let opaque = dataTypeRef?.toOpaque()
var contentsOfKeychain: NSString?
if let op = opaque? {
let retrievedData = Unmanaged<NSData>.fromOpaque(op).takeUnretainedValue()
//println("Retrieved the following data from the keychain: \(retrievedData)")
var str = NSString(data: retrievedData, encoding: NSUTF8StringEncoding)
contentsOfKeychain = NSString(data: retrievedData, encoding: NSUTF8StringEncoding)
//println("The decoded string is \(str)")
} else {
//println("Nothing was retrieved from the keychain.")
}
return contentsOfKeychain
}
}
我的问题有解决方案吗？
最佳答案
您的问题是您的tokenExists()方法不检查令牌是否存在。相反，它假定tokenExists（如!末尾的let token:NSString = loadToken()!所示），然后仅检查它是否为空字符串。
尝试以下tokenExists()方法：
func tokenExists() -> Bool {
var result = false
if let token = loadToken() {
// the token exists, but is it blank?
if token != "" {
// no, the token is not blank
result = true
}
}
return result
}
关于ios - 钥匙串(keychain)类不适用于iPhone 4s/5和iPad，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/26438767/