properties - Error in Swift class: Property not initialized at super.init call -


i have 2 classes, shape , square

class shape {     var numberofsides = 0     var name: string     init(name:string) {         self.name = name     }     func simpledescription() -> string {         return "a shape \(numberofsides) sides."     } }  class square: shape {     var sidelength: double      init(sidelength:double, name:string) {         super.init(name:name) // error here         self.sidelength = sidelength         numberofsides = 4     }     func area () -> double {         return sidelength * sidelength     } }

with implementation above error:

property 'self.sidelength' not initialized @ super.init call     super.init(name:name)

why have set self.sidelength before calling super.init?

quote swift programming language, answers question:

“swift’s compiler performs 4 helpful safety-checks make sure two-phase initialization completed without error:”

safety check 1 “a designated initializer must ensure of “properties introduced class initialized before delegates superclass initializer.”

excerpt from: apple inc. “the swift programming language.” ibooks. https://itunes.apple.com/us/book/swift-programming-language/id881256329?mt=11


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