Arrays 按对象INT快速筛选对象数组!财产
这是我的目标Arrays 按对象INT快速筛选对象数组!财产,arrays,swift,filter,properties,int,Arrays,Swift,Filter,Properties,Int,这是我的目标 class TicketsCellModel: NSObject { var title: String? var text: String? var price: String? var tintColor: UIColor? var quantity: Int? } 这是一些随机数据 var ticketCellModels: [TicketsCellModel] = { var cellOne = TicketsCellMo
class TicketsCellModel: NSObject {
var title: String?
var text: String?
var price: String?
var tintColor: UIColor?
var quantity: Int?
}
这是一些随机数据
var ticketCellModels: [TicketsCellModel] = {
var cellOne = TicketsCellModel()
cellOne.title = "Standard Entry"
cellOne.text = "This is aa standard entry ticket, it's not sutiable for special events please see the plus ticket for that."
cellOne.price = "£8.35"
cellOne.tintColor = UIColor.white
cellOne.quantity = 0
var cellThree = TicketsCellModel()
cellThree.title = "Standard with re-entry"
cellThree.text = "This is a standard entry ticket but you can come and go as you please during the night."
cellThree.price = "£8.99"
cellThree.tintColor = UIColor.white
cellThree.quantity = 2
var cell6 = TicketsCellModel()
cell6.title = "Plus Entry"
cell6.text = "This is the plus entry ticket for special events."
cell6.price = "£9.99"
cell6.tintColor = UIColor.rgb(red: 192, green: 192, blue: 192)
cell6.quantity = 0
var cell9 = TicketsCellModel()
cell9.title = "VIP Entry"
cell9.text = "Here is some more text that is to act as a description for this thing you will purchase."
cell9.price = "£12.99"
cell9.tintColor = UIColor.rgb(red: 255, green: 215, blue: 0)
cell9.quantity = 4
return [cellOne, cellThree, cell6, cell9]
}()
我现在正在尝试生成一个新的TicketCellModel数组,但只使用那些数量大于0的数组。我可以按标题“S”开头的人进行以下筛选
但如果我把它调整到
let filteredTicketCellModels = ticketCellModels.filter( { return ($0.quantity? > 0)! } )
for item in filteredTicketCellModels {
print("qty: \(item.quantity)")
}
我得到“二进制运算符'>'不能应用于'Int'和'Int'类型的操作数。我找不到任何例子来说明我是如何对int进行此操作的如果您想要快速而安全的修复,可以使用nil合并运算符
?
使item.quantity=0,当它等于nil时
看起来是这样的:
let filteredTicketCellModels = ticketCellModels.filter( { return ($0.quantity ?? 0 > 0)! } )
for item in filteredTicketCellModels {
print("qty: \(item.quantity)")
}
按标题筛选不会崩溃的原因是,没有一个可选变量包含nil。但是,如果item.title为==到nil,则其末尾的砰砰(!)会导致变量访问崩溃
如果标题(或类中的任何其他变量)从不为零,则应将其声明为仅
var title:String
,末尾不带?
(这意味着您也必须为您的对象实际拥有一个初始值设定项!(这是更好的做法:)如果您想要快速安全的修复,当item.quantity=0等于nil时,可以使用nil合并运算符??
看起来是这样的:
let filteredTicketCellModels = ticketCellModels.filter( { return ($0.quantity ?? 0 > 0)! } )
for item in filteredTicketCellModels {
print("qty: \(item.quantity)")
}
按标题筛选不会崩溃的原因是,没有一个可选变量包含nil。但是,如果item.title为==到nil,则其末尾的砰砰(!)会导致变量访问崩溃
如果标题(或类中的任何其他变量)从不为零,则应将其声明为仅var title:String
,末尾不带?
(这意味着您也必须为对象指定一个初始值设定项!)
首先,您不需要从NSObject
继承。此外,如果不需要引用语义,请使用struct
s
struct TicketsCellModel {
var title: String?
var text: String?
var price: String?
var tintColor: UIColor?
var quantity: Int?
}
实际上不需要使用闭包来创建[ticketcellmodel]
。直接分配元素即可。由于我们使用的是struct
s,因此不需要创建单独的init
var ticketCellModels = [
TicketsCellModel(
title: "Standard Entry",
text: "This is aa standard entry ticket, it's not sutiable for special events please see the plus ticket for that.",
price: "£8.35",
tintColor: UIColor.white,
quantity: 0
),
TicketsCellModel(
title: "Standard with re-entry",
text: "This is a standard entry ticket but you can come and go as you please during the night.",
price: "£8.99",
tintColor: UIColor.white,
quantity: 2
),
TicketsCellModel(
title: "Plus Entry",
text: "This is the plus entry ticket for special events.",
price: "£9.99",
tintColor: UIColor.white,
quantity: 0
),
TicketsCellModel(
title: "VIP Entry",
text: "Here is some more text that is to act as a description for this thing you will purchase.",
price: "£12.99",
tintColor: UIColor.white,
quantity: 4
)
]
现在,如果您需要访问一个可选文件,则必须首先将其展开。最安全的方法是使用if let
构造或使用
在上面的示例中,初始化期间没有未知变量,因此非可选属性可能更适合。那你就不用打开任何东西了
添加建议所有属性都为常量。方法是将所有var
s替换为let
s。如果需要更改特性,可以创建一个新对象,从旧对象复制特性,并将新值添加到已更改的特性中
首先,您不需要从NSObject
继承。此外,如果不需要引用语义,请使用struct
s
struct TicketsCellModel {
var title: String?
var text: String?
var price: String?
var tintColor: UIColor?
var quantity: Int?
}
实际上不需要使用闭包来创建[ticketcellmodel]
。直接分配元素即可。由于我们使用的是struct
s,因此不需要创建单独的init
var ticketCellModels = [
TicketsCellModel(
title: "Standard Entry",
text: "This is aa standard entry ticket, it's not sutiable for special events please see the plus ticket for that.",
price: "£8.35",
tintColor: UIColor.white,
quantity: 0
),
TicketsCellModel(
title: "Standard with re-entry",
text: "This is a standard entry ticket but you can come and go as you please during the night.",
price: "£8.99",
tintColor: UIColor.white,
quantity: 2
),
TicketsCellModel(
title: "Plus Entry",
text: "This is the plus entry ticket for special events.",
price: "£9.99",
tintColor: UIColor.white,
quantity: 0
),
TicketsCellModel(
title: "VIP Entry",
text: "Here is some more text that is to act as a description for this thing you will purchase.",
price: "£12.99",
tintColor: UIColor.white,
quantity: 4
)
]
现在,如果您需要访问一个可选文件,则必须首先将其展开。最安全的方法是使用if let
构造或使用
在上面的示例中,初始化期间没有未知变量,因此非可选属性可能更适合。那你就不用打开任何东西了
添加建议所有属性都为常量。方法是将所有
var
s替换为let
s。如果需要更改属性,您可以创建一个新对象,从旧对象复制属性,并将新值添加到已更改的属性中。好的,因此有两种解决方案可用
let filteredTicketCellModels = ticketCellModels.filter( { return ($0.quantity ?? 0 > 0) } )
二是,-
let filteredTicketCellModels = ticketCellModels.filter( { return $0.quantity != 0 } )
我还将quantity的默认值设置为零。好的,因此两种解决方案都有效
let filteredTicketCellModels = ticketCellModels.filter( { return ($0.quantity ?? 0 > 0) } )
二是,-
let filteredTicketCellModels = ticketCellModels.filter( { return $0.quantity != 0 } )
我还将quantity的默认值设置为零。为什么这些字段是可选的?你什么时候会有一张没有标题、价格或数量的票?为什么这些字段是可选的?你什么时候会有一张没有标题、价格或数量的票?哦!我懂了。我也设法让它适合我正在做的事情。让filteredTicketCellModels=ticketCellModels.filter({return$0.quantity!=0})这种方法会起作用,但不会过滤掉任何数量的nil(它看起来像是你在强制展开时遇到的),我不确定你想要还是不想要。哦!我懂了。我也设法让它适合我正在做的事情。让filteredTicketCellModels=ticketCellModels.filter({return$0.quantity!=0})这种方法会起作用,但不会过滤掉任何数量的nil(它看起来像是在强制展开时发生崩溃),我不确定您想要还是不想要。