Swift - 自定义UIAlertController的样式1（修改标题、按钮的字体和颜色）

一、修改标题的字体和颜色

1，效果图

2，自定义UIAlertController类

import UIKit

class MyAlertController: UIAlertController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        //标题字体样式（红色，字体放大）
        let titleFont = UIFont.systemFont(ofSize: 20)
        let titleAttribute = NSMutableAttributedString.init(string: self.title!)
        titleAttribute.addAttributes([NSFontAttributeName:titleFont,
                                      NSForegroundColorAttributeName:UIColor.red],
                                     range:NSMakeRange(0, (self.title?.characters.count)!))
        self.setValue(titleAttribute, forKey: "attributedTitle")
        
        //消息内容样式（灰色斜体）
        let messageFontDescriptor = UIFontDescriptor.init(fontAttributes: [
            UIFontDescriptorFamilyAttribute:"Arial",
            UIFontDescriptorNameAttribute:"Arial-ItalicMT",
            ])
        
        let messageFont = UIFont.init(descriptor: messageFontDescriptor, size: 13.0)
        let messageAttribute = NSMutableAttributedString.init(string: self.message!)
        messageAttribute.addAttributes([NSFontAttributeName:messageFont,
                                        NSForegroundColorAttributeName:UIColor.gray],
                                    range:NSMakeRange(0, (self.message?.characters.count)!))
        self.setValue(messageAttribute, forKey: "attributedMessage")
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

3，使用样例

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    override func viewDidAppear(_ animated: Bool){
        super.viewDidAppear(animated)
        
        let alertController = MyAlertController(title: "系统提示",
                                                message: "您确定要离开 hangge.com 吗？",
                                                preferredStyle: .alert)
        let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
        let okAction = UIAlertAction(title: "好的", style: .default, handler: {
            action in
            print("点击了确定")
        })
        alertController.addAction(cancelAction)
        alertController.addAction(okAction)
        self.present(alertController, animated: true, completion: nil)
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

二、修改按钮的样式

1，修改按钮颜色

（2）为方便使用，我们这里通过继承 UIAlertController 实现一个自定义的类：MyAlertController。并在其 addAction 方法中动态改变按钮样式。

import UIKit

class MyAlertController: UIAlertController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    override func addAction(_ action: UIAlertAction) {
        super.addAction(action)
        //通过tintColor实现按钮颜色的修改。
        self.view.tintColor = UIColor.orange
        //也可以通过设置 action.setValue 来实现
        //action.setValue(UIColor.orange, forKey:"titleTextColor")
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

2，在按钮上添加图标

（1）下面我们在确定和取消按钮上分别添加相应的图标，同时两个按钮的文字颜色也不一样。

（2）同样，我们在 UIAlertController 的 addAction 方法中动态改变按钮样式。

import UIKit

class MyAlertController: UIAlertController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    override func addAction(_ action: UIAlertAction) {
        super.addAction(action)
        
        //设置确定按钮图标和样式
        if action.style == .default {
            //使用图片原来颜色
            let iconImage = UIImage(named:"tick")?.withRenderingMode(.alwaysOriginal)
            action.setValue(iconImage, forKey: "image")
            action.setValue(UIColor.green, forKey:"titleTextColor")
            
        }
        //设置取消按钮图片和样式
        else if  action.style == .cancel {
            let iconImage = UIImage(named:"multiply")?.withRenderingMode(.alwaysOriginal)
            action.setValue(iconImage, forKey: "image")
            action.setValue(UIColor.red, forKey:"titleTextColor")
        }
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}