failable initialiser swift simple example

failable initialiser swift simple example

In swift, Failable initialisers are used with structure,class and enumeration. When it is not sure that a property within class or structure or enumeration will be initialised then failable initialisers are used.

For this, we write initialiser with init? syntax and if initialisation succeeds then value is assigned or else nil value is assigned.

Example Code

class FailInit{
    let a:String
    let b:Int

    init?(a:String,b:Int){
        if a.isEmpty {
            return nil
        }
        else{
        self.a = a
        }

        if b>0 {
            self.b = b
        }
        else{
            return nil
        }
    }
    
}

var failObj = FailInit(a:"",b: 5)
failObj?.a     //nil

var failObj1 = FailInit(a:"Hello",b: 1)
failObj1?.a    //Hello

var failObj2 = FailInit(a:"Hey", b:0)
failObj2?.a    //nil

class FailInit{

let a:String

let b:Int

init?(a:String,b:Int){

if a.isEmpty {

return nil

}

else{

self.a = a

}

if b>0 {

self.b = b

}

else{

return nil

}

var failObj = FailInit(a:"",b: 5)

failObj?.a //nil

var failObj1 = FailInit(a:"Hello",b: 1)

failObj1?.a //Hello

var failObj2 = FailInit(a:"Hey", b:0)

failObj2?.a //nil

Example Code

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