不好的代码

今天在检视代码，发现一些问题，顺便贴出来，第一篇简书文章

滥用guard

首先看一下官方对guard关键字的说明

Early Exit
A guard statement, like an if statement, executes statements depending on the Boolean value of an expression. You use a guard statement to require that a condition must be true in order for the code after the guard statement to be executed. Unlike an if statement, a guard statement always has an else clause—the code inside the else clause is executed if the condition is not true.”
摘录来自: Apple Inc. “The Swift Programming Language (Swift 3 beta)”。 iBooks. https://itun.es/us/k5SW7.l

而下面的例子并不是对异常情况进行判断，所以该场景下应该使用if或switch

guard orderData["workOrderType"].numberValue == OrderType.ServiceOrder.rawValue else {
    orderCell.orderType = .WorkOrder
    orderCell.configCell(orderData, indexPatch: indexPath)
    return orderCell
}

使用硬代码（魔鬼数字）

cell.remarkLabel.preferredMaxLayoutWidth = (screenWidth - 320) + 304

代码挤成一坨

下面的代码有几个问题

• 代码挤成一坨
• 用代码去生成按钮（不推荐）
• 用代码去生成按钮的目的实际上是想设置按钮的颜色，这个可能通过tintColor很方便地处理

let cancelButton = UIButton(type: .System)
cancelButton.frame = CGRectMake(0, 0, 42, 20)
cancelButton.setTitle(cancelButtonTitle, forState: .Normal)
cancelButton.titleLabel?.font = UIFont.boldSystemFontOfSize(16)
cancelButton.setTitleColor(UIColor.colorWithHexString("#29b6f6"), forState: .Normal)
picker.setCancelButton(UIBarButtonItem(customView: cancelButton))
let doneButton = UIButton(type: .System)
doneButton.frame = CGRectMake(0, 0, 50, 20)
doneButton.setTitle(doneButtonTitle, forState: .Normal)
doneButton.titleLabel?.font = UIFont.boldSystemFontOfSize(16)
doneButton.setTitleColor(UIColor.colorWithHexString("#29b6f6"), forState: .Normal)
picker.setDoneButton(UIBarButtonItem(customView: doneButton))

比较好的代码应该这样（忽略selector的处理）

let cancelButton = UIBarButtonItem(title: "Cancel", style: .Plain, target: self, action: nil)
cancelButton.tintColor = UIColor.colorWithHexString("#29b6f6")
picker.setCancelButton(cancelButton)

let doneButton = UIBarButtonItem(title: "Done", style: .Plain, target: self, action: nil)
doneButton.tintColor = UIColor.colorWithHexString("#29b6f6")
picker.setDoneButton(doneButton)

类型初始化有误

下面代码中的变量不可能为浮点型，却声明为浮点型

var currentPage = 1.0
var pageSize = 10.0

毫无意义的重载

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
}

override func viewWillDisappear(animated: Bool) {
    super.viewWillDisappear(animated)
}

Bean使用复数

Bean是抽象的，不应该为复数
public static class WorkOrdersBean

多层if嵌套

图片来自网络