mshrwtnb / alrt

An easier constructor for UIAlertController. Present an alert from anywhere.

ALRT

An easier constructor for UIAlertController. Present an alert from anywhere like this.

ALRT.create(.alert, title: "Alert?").addOK().addCancel().show()

Table of Contents

• Features
• Requirements
• Installation
• Usage
• License

Features

• Chainable UIAlertController Setup Methods
• Support .alert and .actionSheet UIAlertController.Style
• Support UITextfield UIAlertAction(.alert only)
• Returns Result whether an alert is successfully displayed. In other words, Unit Testable.

Requirements

• Xcode 10.2+
• Swift 5.0
• iOS 9.0+

Installation

Carthage

github "mshrwtnb/ALRT" ~> 1.3.7

Cocoapods

pod repo update
pod 'ALRT', '~> 1.3.7'

Usage

Basics

.alert

import ALRT

// Instantiate an .alert-type UIAlertController with OK and Cancel actions. Finally, present the alert by calling `show()`.
ALRT.create(.alert, title: "Title", message: "Message").addOK().addCancel().show()

.actionSheet

// Instantiate an .actionSheet-type UIAlertController.
ALRT.create(.actionSheet, message: "Action Sheet")
    .addAction("Option A")
    .addAction("Option B")
    .addDestructive("Destructive Option")
    .show() 

Action Types

Each action comes with different UIAlertAction.Style.

ALRT.create(.alert, title: "Action Types?")
    .addAction("🏂") // .default if not specified
    .addOK() // .default
    .addCancel("❌") // .cancel
    .addDestructive("💣") // .destructive
    .show()

Custom Title

OK and Cancel actions have default titles in English; "OK" and "Cancel". Here, we're overriding the titles in Japanese.

ALRT.create(.alert, title: "Actions In Japanese?").addOK("オーケー").addCancel("キャンセル").show()

Action Handling

Each action has handler that is called when user taps the action. The closure takes two parameters: UIAlertAction and [UITextField]?. The former is self-explanatory. The latter is present if text field(s) is/are added to the alert.

ALRT.create(.alert, title: "Action Handling")
    .addOK() { action, textFields in
        print("\(action.title!) tapped")
    }
    .show()

Result Handling

show() has a completion handler that takes Result. You can ensure if the alert was shown successfully or not. This is useful for unit tests.

ALRT.create(.alert, title: "Result Handling")
    .addOK()
    .show() { result in
        switch result {
        case .success:
            print("Alert is successfully shown")
        case .failure(let error):
            print("Error occurred. \(error.localizedDescription)")
        }
    }

TextField(s)

Textfield(s) can be added to an alert in an use-case such as login.

enum TextFieldIdentifier: Int {
    case username
    case password
}

ALRT.create(.alert, title: "Enter your credentials")
    // Configure textfield
    .addTextField { textfield in
        textfield.placeholder = "Username"
        textfield.tag = TextFieldIdentifier.username.rawValue
    }
    .addTextField() { textField in
        textField.placeholder = "Password"
        textField.isSecureTextEntry = true
        textField.tag = TextFieldIdentifier.password.rawValue
    }
    // If an user selects "Login", textfields above are retrieved in the trailing closure. Distinguish one from another with a tag or identifier.
    .addAction("Login") { _, textfields in
        for textField in textfields ?? [] {
            if let identifier = TextFieldIdentifier(rawValue: textField.tag) {
                switch identifier {
                case .username:
                    // Extract username
                case .password:
                    // Extract password
                }
            }
        }
    }
    .addCancel()
    .show()

Changing source ViewController to present from

Although ALRT can present an alert anywhere, you might want to specify a source view controller for some reason. This can be done easily by passing a view controller to show().

ALRT.create(.alert, title: "Source?")
    .addOK()
    .show(self) // self = source view controller

Default Configuration

Set default tintColor and titles for OK and Cancel buttons.

ALRT.defaultConfiguration = .init(
    tintColor: UIColor.blue,
    okTitle: "OK👍",
    cancelTitle: "Cancel👎"
)

License

ALRT is released under the MIT license. See LICENSE for details.

alrt's Issues

Constraint issue with alert actionsheet.

Error

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2020-04-23 15:21:48.556790-0600 Banky[71185:1795813] [LayoutConstraints] Unable to simultaneously satisfy constraints.
	Probably at least one of the constraints in the following list is one you don't want. 
	Try this: 
		(1) look at each constraint and try to figure out which you don't expect; 
		(2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x6000032b6080 UIView:0x7fb0ba45f9e0.width == - 16   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x6000032b6080 UIView:0x7fb0ba45f9e0.width == - 16   (active)>

This is what I'm calling and the above warning occurs.

        ALRT.create(.actionSheet)
            .addAction("Terms of Use") { _, _ in
                self.performSegue(withIdentifier: "termsToWebView", sender: nil)
            }
        .addAction("Privacy Policy") { _, _ in
            self.performSegue(withIdentifier: "privacyToWebView", sender: nil)
        }
        .addCancel()
        .show()

画面遷移後アラートが表示されない。

画面遷移のあるアプリで、遷移後の画面でALRTを使おうとすると、以下のようなエラーが出てアラートが表示されません。
Demo[26163:424735] Warning: Attempt to present <UIAlertController: 0x7fd9e5044a00> on <Demo.FirstViewController: 0x7fd9e7c07930> whose view is not in the window hierarchy!

FirstViewControllerといのは、demoのプロジェクトでDemoViewControllerに遷移するViewControllerです。

表示するViewControllerがうまく指定できていないと思うのですが、対策はあるでしょうか？
問題が発生するDemoを含んだZipを添付します。
ALRT-master_edited.zip

iOS13で、アラートが表示されなくなる場合がある

iOS 13にて、UIViewControllerをセットせずにshow()をコールすると、下記のような現象が起こるようです。
お手数ですが、確認をお願いできませんでしょうか。

現象

1.デバッグに以下の警告が表示される

Keyboard cannot present view controllers (attempted to present <UIAlertController: 0x------->

2.アラートが表示できなくなる

アラートを頻繁に表示していると、何かのタイミングで、それ以降、アラートが表示できなくなります。
詳細な再現条件は分かっていませんが、下記のコードのように、テキストフィールドを持つアラートを表示し、キーボードが表示されているタイミングで、OK等のクロージャから次のアラートを表示すると、私の環境（6世代iPad, iPadOS 13.4.1）ではほぼ再現します。
ただ、頻度は低いですが、キーボードを表示しなくても、同じ現象が発生する場合があります。
この現象が発生すると、以降、アラートを表示しようとすると、デバッグエリアに、下記のような警告が表示されます。

[View] First responder error: non-key window attempting reload - allowing due to manual keyboard (first responder window is <UIRemoteKeyboardWindow: 0x105869c00; frame = (0 0; 768 1024); opaque = NO; autoresize = W+H; layer = <UIWindowLayer: 0x28157ed00>>, key window is <UITextEffectsWindow: 0x1049365e0; frame = (0 0; 768 1024); opaque = NO; autoresize = W+H; layer = <UIWindowLayer: 0x2815c6040>>)

ALRT.create(.alert, title: "テスト", message: "テスト")
	.addTextField { textfield in
		textfield.placeholder = ""
		textfield.tag = 0
	}
	.addOK() { action, textFields in
		// このアラートは表示されず、以降、アラートが表示できなくなる
		ALRT.create(.alert, title: "エラー", message: "エラー").addOK().show()
	}
	.addCancel()
	.show()

3.アラートのテキストエリアにフォーカスがあたらず、キーボードが自動表示されない

原因

UIApplication.topMostViewController()が、キーボード用のWindow（UIRemoteKeyboardWindow）を返しているのが原因ではないでしょうか。
下記のように修正したところ、問題は発生しなくなりました。

private extension UIApplication {
    func topMostViewController() -> UIViewController? {
	let uiWindow: UIWindow? = {
		for window in windows.reversed() {
			if NSStringFromClass(type(of: window)) == "UIWindow" {
				return window
			}
		}
		return windows.last
	}()
		
	guard let keyWindow = uiWindow else {
            return nil
        }
        return keyWindow.rootViewController?.topMostViewController()
    }
}