修改UITextField的leftView/rightView

重写几个方法即可

class RNSearchTextField: UITextField {
    
    //  重写
    override func leftViewRect(forBounds bounds: CGRect) -> CGRect {
        var padding = super.leftViewRect(forBounds: bounds)
        padding.origin.x += 5
        return padding
    }
    
    override func rightViewRect(forBounds bounds: CGRect) -> CGRect {
        var padding = super.rightViewRect(forBounds: bounds)
        padding.origin.x -= 5
        return padding
    }
    
    override func textRect(forBounds bounds: CGRect) -> CGRect {
        var padding = super.textRect(forBounds: bounds)
        padding.origin.x += 5
        return padding
    }
    
    override func editingRect(forBounds bounds: CGRect) -> CGRect {
        var padding = super.editingRect(forBounds: bounds)
        padding.origin.x += 5
        return padding
    }
    
    override func placeholderRect(forBounds bounds: CGRect) -> CGRect {
        var padding = super.placeholderRect(forBounds: bounds)
        padding.origin.x += 5
        return padding
    }
}

`