Property wrapper can be used with class, structure, and enumeration.

According to swift doc “A property wrapper adds a layer of separation between code that manages how a property is stored and the code that defines a property”. In another way, it encapsulates read and write access and provides additional behavior to property.

By using the property wrapper we can reuse the code by applying it to multiple properties. It can be use with class, structure, and enumeration. For better understanding, we will take an example.

@propertyWrapper
struct EmailValidationWrapper{
    
    var email:String
    var wrappedValue:String{
        get{
            checkValidEmail(emai: email) ? email : ""
        }set{
            self.email = newValue
        }
    }
    
    init(email:String) {
        self.email = email
    }
    func checkValidEmail(emai: String) -> Bool {
         let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,64}"
         let emailTest = NSPredicate(format: "SELF MATCHES %@", emailRegex)
         return (emailTest.evaluate(with: emai))
     }

}


struct Employee {
    var name:String
    @EmailValidationWrapper var email:String
    
    func doFurther(){
        if email == ""{
            print("can not move further")
        }else{
            print("proceed further")
            //Do things
        }
    }
}

@propertyWrapper

struct EmailValidationWrapper{

var email:String

var wrappedValue:String{

get{

checkValidEmail(emai: email) ? email : ""

}set{

self.email = newValue

}

init(email:String) {

self.email = email

}

func checkValidEmail(emai: String) -> Bool {

let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,64}"

let emailTest = NSPredicate(format: "SELF MATCHES %@", emailRegex)

return (emailTest.evaluate(with: emai))

}

struct Employee {

var name:String

@EmailValidationWrapper var email:String

func doFurther(){

if email == ""{

print("can not move further")

}else{

print("proceed further")

//Do things

}

        let emp = Employee(name: "Test", email: EmailValidationWrapper(email: "testexample.com"))
        emp.doFurther() // Output can not move further

        let emp1 = Employee(name: "Test", email: EmailValidationWrapper(email: "test@example.com"))
        emp1.doFurther() // proceed further

let emp = Employee(name: "Test", email: EmailValidationWrapper(email: "testexample.com"))

emp.doFurther() // Output can not move further

let emp1 = Employee(name: "Test", email: EmailValidationWrapper(email: "[email protected]"))

emp1.doFurther() // proceed further

In the above example, we have created a structure name EmailValidationWrapper which has @propertyWrapper attribute. Here you have to define a wrappedValue property unless you will get an error like “Property wrapper type ‘EmailValidationWrapper’ does not contain a non-static property named ‘wrappedValue'”.

We have created a emailValidator method name “checkValidEmail” from getter we are calling this method. We have created another structure named Employee and for email validation, we have used our structure “EmailValidationWrapper”. And by using the property wrapper we have created our maintenance code and can be use multiple times.

Thanks for reading this blog.

For details, understanding you can visit the swift doc. You can also check other blogs from here. if you have any issues or suggestions you can leave your query/suggestion in the comment section.

Vicky Kumar 26 August 2021

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Property wrapper in iOS Swift

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Property wrapper in iOS Swift

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