当我尝试获取我的 keyChain 值时,它返回一个包含以下内容的字符串:
Optional("[thing in the KeyChain]")
因此,我尝试使用循环删除“可选”:
var str = KeychainService.loadToken()
for(var i = 0; i < 9 ; i++)
{
str[i] = ""
}
但我得到一个错误:NSString 没有名为“下标”的成员
KeychainService 类:
import Foundation
import Security
let serviceIdentifier = "MySerivice"
let userAccount = "authenticatedUser"
let accessGroup = "MySerivice"
// Arguments for the keychain queries
let kSecClassValue = kSecClass.takeRetainedValue() as NSString
let kSecAttrAccountValue = kSecAttrAccount.takeRetainedValue() as NSString
let kSecValueDataValue = kSecValueData.takeRetainedValue() as NSString
let kSecClassGenericPasswordValue = kSecClassGenericPassword.takeRetainedValue() as NSString
let kSecAttrServiceValue = kSecAttrService.takeRetainedValue() as NSString
let kSecMatchLimitValue = kSecMatchLimit.takeRetainedValue() as NSString
let kSecReturnDataValue = kSecReturnData.takeRetainedValue() as NSString
let kSecMatchLimitOneValue = kSecMatchLimitOne.takeRetainedValue() as NSString
class KeychainService: NSObject {
/**
* Exposed methods to perform queries.
* Note: feel free to play around with the arguments
* for these if you want to be able to customise the
* service identifier, user accounts, access groups, etc.
*/
internal class func saveToken(token: NSString) {
self.save(serviceIdentifier, data: token)
}
internal class func loadToken() -> NSString? {
var token = self.load(serviceIdentifier)
return token
}
/**
* Internal methods for querying the keychain.
*/
private class 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: [kSecClassGenericPasswordValue, service, userAccount, dataFromString], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecValueDataValue])
// Delete any existing items
SecItemDelete(keychainQuery as CFDictionaryRef)
// Add the new keychain item
var status: OSStatus = SecItemAdd(keychainQuery as CFDictionaryRef, nil)
}
private class func load(service: NSString) -> String? {
// Instantiate a new default keychain query
// Tell the query to return a result
// Limit our results to one item
var keychainQuery: NSMutableDictionary = NSMutableDictionary(objects: [kSecClassGenericPasswordValue, service, userAccount, kCFBooleanTrue, kSecMatchLimitOneValue], forKeys: [kSecClassValue, kSecAttrServiceValue, kSecAttrAccountValue, kSecReturnDataValue, kSecMatchLimitValue])
var dataTypeRef :Unmanaged<AnyObject>?
// Search for the keychain items
let status: OSStatus = SecItemCopyMatching(keychainQuery, &dataTypeRef)
let opaque = dataTypeRef?.toOpaque()
var contentsOfKeychain: String?
if let op = opaque? {
let retrievedData = Unmanaged<NSData>.fromOpaque(op).takeUnretainedValue()
// Convert the data retrieved from the keychain into a string
contentsOfKeychain = NSString(data: retrievedData, encoding: NSUTF8StringEncoding)
} else {
println("Nothing was retrieved from the keychain. Status code \(status)")
}
return contentsOfKeychain
}
}
我只是不想删除 str 周围的 Optional 东西 或者有更好的方法吗?
我从以下位置获取此代码:
http://matthewpalmer.net/blog/2014/06/21/example-ios-keychain-swift-save-query/
最佳答案
你得到 Optional("")
因为可选值没有被解包。您需要在对象之后放置一个 !
并且您将不会再获得 Optional("")
位。我会向您展示代码,但您没有向我们展示 print()
语句。我在下面制作了一些示例,我认为它们会重现该问题,但我还没有尝试过。
var value:String?
value = "Hello, World"
print("The Value Is \(value)") // Prints "The Value Is Optional(Hello, World)"
print("The Value Is \(value!)")// Prints "The Value Is Hello, World"
我希望这能回答您的问题或至少为您指明正确的方向,只需询问您是否需要更多信息或更好的示例。
关于swift - 尝试从 KeyChain 获取值时获取可选 (""),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25488162/