我正在做一个项目,在像这样迭代 for in 循环时遇到了这个错误:
class CustomClass {
var nameNum : Int { didSet { self.name = "CustomClass \(nameNum)" } }
var name : String
init() {
nameNum = 0
self.name = "CustomClass \(nameNum)"
}
}
var myArray : [CustomClass] = [CustomClass](repeating: CustomClass(), count: 5)
for _class in myArray.indices {
myArray[_class].nameNum = _class
}
print("\n")
for _class in myArray.indices {
print("Item \(_class): \(myArray[_class].name)")
}
我得到以下输出:
Item 0: CustomClass 4
Item 1: CustomClass 4
Item 2: CustomClass 4
Item 3: CustomClass 4
Item 4: CustomClass 4
这对我来说没有意义,因为我认为我会得到以下输出:
Item 0: CustomClass 0
Item 1: CustomClass 1
Item 2: CustomClass 2
Item 3: CustomClass 3
Item 4: CustomClass 4
对于为什么这不起作用或如何修复它的任何帮助,我们将不胜感激,谢谢!
最佳答案
您应该将数组初始化更改为
var myArray : [CustomClass] = (0..<5).map { _ in CustomClass() }
来自
var myArray : [CustomClass] = [CustomClass](repeating: CustomClass(), count: 5)
完整代码:
class CustomClass {
var nameNum : Int { didSet { self.name = "CustomClass \(nameNum)" } }
var name : String
init() {
nameNum = 0
self.name = "CustomClass \(nameNum)"
}
}
var myArray : [CustomClass] = (0..<5).map { _ in CustomClass() }
for _class in myArray.indices {
myArray[_class].nameNum = _class
}
print("\n")
for _class in myArray.indices {
print("Item \(_class): \(myArray[_class].name)")
}
原因是您的代码实际上创建了一个 CustomClass
实例,并将其添加到数组的所有 5 个索引处,而您期望有 5 个不同的 CustomClass
实例。如果同一个实例被添加 5 次,那么所有实例都将具有最后一个设置值,在您的情况下为 4。
Item 0: CustomClass 0
Item 1: CustomClass 1
Item 2: CustomClass 2
Item 3: CustomClass 3
Item 4: CustomClass 4
关于Swift For In Loop 遍历一组自定义类不起作用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/45362819/