IOS 13 : spacing Issue with UITextField rightView

Question

我在 IOS 13 中遇到 UITextField 右 View 的间距问题，请参阅我的以下代码以及 ios 13 和 ios 12.4 的屏幕截图

在 IOS 12.4 模拟器中，在 UITextField 的右 View (UIButton)中显示适当的空间

在 IOS 13.0 模拟器中，UITextField 的右 View (UIButton)存在间距问题

let dropdownButton = UIButton(frame: CGRect(x: 0, y: 0, width: 50, height: txtField.frame.height))
dropdownButton.backgroundColor = UIColor.clear
dropdownButton.setImage(UIImage(named: "ic_DownArrow"), for: UIControl.State())            
txtField.rightView = dropdownButton           
txtField.rightViewMode = .always

Answer 1

显然这是 rightViewRect(forBounds:) 在 iOS 13 Beta 5 中的行为方式的变化。

来自 iOS 和 iPadOS 13 开发者 Beta 5 发行说明:

UIKit - Resolved Issues

Prior to iOS 13, UITextField assumed that the frames of its leftView and rightView were correctly set when assigned and would never change. Starting in iOS 13, the implementation of leftViewRect(forBounds:) and rightViewRect(forBounds:) now ask the view for its systemLayoutSizeFitting(:). To achieve the previous behavior when linking against and running on iOS 13, add explicit sizing constraints on the view, wrap it in a plain UIView, or subclass the view and implement systemLayoutSizeFitting(:). (51787798)

因此，将自动布局约束添加到您添加到 rightView 的自定义 View

示例:-

override func rightViewRect(forBounds bounds: CGRect) -> CGRect {
        return CGRect(x: bounds.width - 30, y: 0, width: 20 , height: bounds.height)
    }