我不确定这里发生了什么事情,这似乎应该非常简单明了。我有一个含有可变变量的协议,并且有一个带有mutating函数的扩展程序。当我尝试在testClass.testFunc中使用扩展程序中声明的mtkAnimQueAppend时,会出现以下错误:"Cannot use mutating member on immutable value: 'self' is immutable.
protocol MTKAnimateValueDelegate {
var mtkAnimQue:[MTKAnimateValue]? {get set}
}
extension MTKAnimateValueDelegate {
///Adds element to que
mutating func mtkAnimQueAppend(element:MTKAnimateValue) {
if mtkAnimQue != nil {
mtkAnimQue?.append(element)
} else {
mtkAnimQue = [element]
}
}
}
class testClass: MTKAnimateValueDelegate {
var mtkAnimQue:[MTKAnimateValue]?
func testFunc() {
var animValue = MTKAnimateValue(fromValue: 10, toValue: 20, inSeconds: 2)
animValue.isAnimating = true
mtkAnimQueAppend(animValue) //ERROR: "Cannot use mutating member on immutable value: 'self' is immutable
}
}