Essential Books

Keychain Access Control TouchID with password fallback

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Keychain allows to save items with special SecAccessControl attribute which will allow to get item from Keychain only after user will be authenticated with Touch ID (or passcode if such fallback is allowed). App is only notified whether the authentication was successful or not, whole UI is managed by iOS.

First, SecAccessControl object should be created:

Swift 

let error: Unmanaged<CFError>?

guard let accessControl = SecAccessControlCreateWithFlags(kCFAllocatorDefault, kSecAttrAccessibleWhenPasscodeSetThisDeviceOnly, .userPresence, &error) else {
    fatalError("Something went wrong")
}

Next, add it to the dictionary with kSecAttrAccessControl key (which is mutually exclusive with kSecAttrAccessible key you’ve been using in other examples):

Swift 

var dictionary = [String : Any]()

dictionary[kSecClass as String] = kSecClassGenericPassword
dictionary[kSecAttrLabel as String] = "com.me.myapp.myaccountpassword" as CFString
dictionary[kSecAttrAccount as String] = "My Name" as CFString
dictionary[kSecValueData as String] = "new_password!!".data(using: .utf8) as! CFData
dictionary[kSecAttrAccessControl as String] = accessControl

And save it as you’ve done before:

Swift 

let lastResultCode = SecItemAdd(query as CFDictionary, nil)

To access stored data, just query Keychain for a key. Keychain Services will present authentication dialog to the user and return data or nil depending on whether suitable fingerprint was provided or passcode matched.

Optionally, prompt string can be specified:

Swift 

var query = [String: Any]()

query[kSecClass as String] = kSecClassGenericPassword
query[kSecReturnData as String] = kCFBooleanTrue
query[kSecAttrAccount as String] = "My Name" as CFString
query[kSecAttrLabel as String] = "com.me.myapp.myaccountpassword" as CFString
query[kSecUseOperationPrompt as String] = "Please put your fingers on that button" as CFString

var queryResult: AnyObject?
let status = withUnsafeMutablePointer(to: &queryResult) {
    SecItemCopyMatching(query as CFDictionary, UnsafeMutablePointer($0))
}

Pay attention that status will be err if user declined, canceled or failed authorization.

Swift 

if status == noErr {
    let password = String(data: queryResult as! Data, encoding: .utf8)!
    print("Password: \(password)")
} else {
    print("Authorization not passed")
}
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Keychain:
* 0Keychain
* Adding a Password to the Keychain
* Keychain Access Control TouchID with password fallback
* Finding a Password in the Keychain
* Updating a Password in the Keychain
* Removing a Password from the Keychain
* Keychain Add Update Remove and Find operations using one file.
Table Of Contents
0 Getting started with iOS
1 UILabel
2 Change Status Bar Color
3 Passing Data between View Controllers
4 Managing the Keyboard
5 UIButton
6 UILocalNotification
7 UIImageView
8 Checking for Network Connectivity
9 Accessibility
10 UITableView
11 Auto Layout
12 UIView
13 UIAlertController
14 MKMapView
15 UIColor
16 NSAttributedString
17 CAAnimation
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20 Concurrency
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24 Safari Services
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29 Swift and Objective-C interoperability
30 NSDate
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32 AVSpeechSynthesizer
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35 Localization
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38 Networking with Alamofire
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60 UIControl - Event Handling with Blocks
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62 UIPageViewController
63 UIAppearance
64 Push Notifications
65 Key Value Coding
66 Initialization idioms
67 Storyboard
68 Background Modes and Events
69 Fastlane
70 CAShapeLayer
71 WKWebView
72 UUID Universally Unique Identifier
73 Categories
74 Handling URL Schemes
75 Realm database
76 ARC Automatic Reference Counting
77 UIPickerView
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82 DispatchGroup
83 GCD Grand Central Dispatch
84 Size Classes and Adaptivity
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86 IBOutlets
87 AWS SDK
88 Debugging Crashes
89 UISplitViewController
90 UISplitViewController
91 UIDevice
92 CloudKit
93 GameplayKit
94 XCode Build Archive From Command Line
95 Unit Testing with XCTest
96 NSData
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98 Deep Linking
99 App Transport Security (ATS)
100 Core Graphics
101 Segues
102 UIDatePicker
103 NSPredicate
104 EventKit
105 NSBundle
106 SiriKit
107 Contacts Framework
108 Dynamically updating a UIStackView
109 Speech Recognition
110 NSURLConnection
111 StoreKit
112 Code signing
113 .ipa file to upload on appstore with ApplicationLoader
114 Resizing UIImage
115 Size Classes and Adaptivity
116 MKDistanceFormatter
117 3D Touch
118 GameCenter Leaderboards
119 Keychain
120 Handle Multiple Environment using Macro
121 Set View Background
122 Block
123 Content Hugging
124 Google Places API
125 Navigation Bar
126 UITextField Delegate
127 App-wide operations
128 UILabel text underlining
129 Cut a UIImage into a circle
130 Make selective UIView corners rounded
131 Convert HTML to NSAttributed string and vice versa
132 Convert NSAttributedString to UIImage
133 CoreImage Filters
134 Face Detection Using CoreImageOpenCV
135 MPMediaPickerDelegate
136 Graph Coreplot
137 NSHTTPCookieStorage
138 FCM Messaging
139 Create Custom Framework
140 Custom Keyboard
141 AirDrop
142 SLComposeViewController
143 AirPrint tutorial
144 UISlider
145 Carthage
146 HealthKit
147 Core SpotLight
148 UI Testing
149 Core Motion
150 QR Code Scanner
151 plist
152 NSInvocation
153 UIRefreshControl TableView
154 WCSessionDelegate
155 AppDelegate
156 App Submission Process
157 MVVM
158 UIStoryboard
159 Basic text file I/O
160 Text To Speech (TTS)
161 MPVolumeView
162 Objective-C Associated Objects
163 Passing Data between View Controllers
164 UIPhoenix
165 Blocks in Queue with MKBlockQueue
166 Simulator
167 BackgroundModes
168 NSArray
169 OpenGL
170 UIScrollView with StackView child
171 Cache online images
172 MVP Architecture
173 UIKit Dynamics
174 Configure Beacons with CoreBluetooth
175 Core Data
176 Extension for rich Push Notification
177 Profiling with Instruments
178 Application rating review request
179 MyLayout
180 UIFont
181 Simulator Builds
182 Simulating Location Using GPX files
183 Custom methods of selection of UITableViewCells
184 Custom methods of selection of UITableViewCells
185 UISegmentedControl
186 SqlCipher integration
187 Custom UITextField
188 Custom UITextField
189 Security
190 Guideline to architecture patterns
191 UIFeedbackGenerator
192 UIKit Dynamics with UICollectionView
193 Multicast Delegates
194 Using image assets
195 UITableViewCell
196 Runtime in Objective-C
197 ModelPresentationStyles
198 CydiaSubstrate tweak
199 Create a video from images
200 Codable
201 FileHandle
202 NSUserActivity
203 Rich Notifications
204 Load images async
205 Adding Swift bridging header
206 Creating an App ID
207 Changing the rootview controller
208 Attributed text in UILabel
209 UITableViewController
210 Contributors