Question

我编写了如下所示的代码。如何打印A4变量？当我这样尝试时，我得到一个错误？

错误：__ lldb_expr_1.Paper

// Paper Factory
// All sizes are mm type
import UIKit


class Paper {
    var weight: Double = 0.0
    var sizeHeight: Double = 0.0
    var sizeWidth:  Double = 0.0

    init(weight: Double, sizeHeight: Double, sizeWidth: Double){
        self.sizeHeight = sizeHeight
        self.sizeWidth = sizeWidth
        self.weight = weight
    }

    func paperPrice(weight: Double, sizeHeight:Double, sizeWidth:Double){
        var price = (sizeHeight * sizeWidth) * weight / 1000
    }
}

var A4 = Paper(weight: 3, sizeHeight: 210, sizeWidth: 297)

println(A4)

Answer 1

试试这个

 NSLog("\(A4)")

它工作得很好......

Answer 2

在错误消息中，lldb指的是LLDB，即Xcode调试器的命令行提示符。打印这些值的正确方法是将NSLog与format specifiers一起使用。例如：

NSLog(@"Value of property : %d", A4.weight)

此外，查看上面的示例代码，price无法在课程级别访问，因为它是在func paperPrice范围内定义的。您可能希望定义与price等类似的weight，并使用A4.price进行访问。

Answer 3

println可以很好地使您的班级符合Printable协议。以这种方式实现你的课程。别忘了添加description属性。

class Paper : Printable{

    var weight: Double = 0.0
    var sizeHeight: Double = 0.0
    var sizeWidth:  Double = 0.0

    var description: String {
        return "Weight: \(weight) sizeHeight: \(sizeHeight) sizeHeight: \(sizeHeight): \(sizeHeight: \(sizeHeight))"
    }
}

Answer 4

您的paperPrice功能没有做任何事情。它将值设置为函数中定义的变量。函数完成后，变量就超出范围。您需要将变量返回到Class之外的内容才能使用它。试试这个：

// Paper Factory
// All sizes are mm type
import UIKit


class Paper {
    var weight: Double = 0.0
    var sizeHeight: Double = 0.0
    var sizeWidth:  Double = 0.0

    init(weight: Double, sizeHeight: Double, sizeWidth: Double){
        self.sizeHeight = sizeHeight
        self.sizeWidth = sizeWidth
        self.weight = weight
    }

    func paperPrice() -> Double {
        var weight = self.weight
        var sizeHeight = self.sizeHeight
        var sizeWidth = self.sizeWidth
        var price: Double = (sizeHeight * sizeWidth) * weight / 1000
        return price
    }
}


var A4paper = Paper(weight: 3, sizeHeight: 210, sizeWidth: 297)
var price = A4paper.paperPrice()

println(price)

Answer 5

确保计算paperPrice的函数返回一个可以打印的值。

<proxies>
        <proxy>
            <active>true</active>
            <protocol>https</protocol>
            <host>localhost</host>
            <port>3132</port> 
        </proxy>
</proxies>

无法在swift中打印变量

5 个答案: