Inset with clearButton in UITextField.

/// left, right Inset.
var textInset: UIEdgeInsets = .zero
/// clearBtn right inset.
var clearInset: CGFloat = 0

private var fRects = FieldRects()
private struct FieldRects {
    var editBox: CGRect = .zero
    var clearBtn: CGRect = .zero
    var leftView: CGRect = .zero
    var rightView: CGRect = .zero
}

override var leftView: UIView? {
    didSet {
        leftViewMode = .always
        fRects.leftView = super.leftViewRect(forBounds: bounds)
    }
}

override var rightView: UIView? {
    didSet {
        rightViewMode = .unlessEditing
        fRects.rightView = super.rightViewRect(forBounds: bounds)
    }
}

override func awakeFromNib() {
    super.awakeFromNib()
    clearButtonMode = .whileEditing
    fRects.editBox = super.editingRect(forBounds: bounds)
    fRects.clearBtn = super.clearButtonRect(forBounds: bounds)
}

override func clearButtonRect(forBounds bounds: CGRect) -> CGRect {
    var rect = fRects.clearBtn
    rect.origin.x -= clearInset
    return rect
}

override func editingRect(forBounds bounds: CGRect) -> CGRect {
    var rect = fRects.editBox
    rect.origin.x += (fRects.leftView.width + textInset.left)
    rect.size.width -= (fRects.rightView.width - textInset.right - rect.origin.x)
    return rect
}
    
override func textRect(forBounds bounds: CGRect) -> CGRect {
    var rect = bounds
    rect.origin.x += (fRects.leftView.width + textInset.left)
    rect.size.width -= (fRects.rightView.width - textInset.right - rect.origin.x)
    return rect
}