Page 123


"duration":"\(self.duration)" ] } }

var movie = film() movie.head = "Swift Properties" movie.duration = 3.09

println(movie.metaInfo["head"]!) println(movie.metaInfo["duration"]!) When we run the above program using playground, we get the following result: Swift Properties 3.09

Computed Properties as Property Observers In Swift to observe and respond to property values Property Observers are used. Each and every time when property values are set property observers are called. Except lazy stored properties we can add property observers to 'inherited' property by method 'overriding'. Property Observers can be defined by either 

Before Storing the value - willset

After Storing the new value - didset

When a property is set in an initializer willset and didset observers cannot be called.

class Samplepgm { var counter: Int = 0{ willSet(newTotal){ println("Total Counter is: \(newTotal)") } didSet{ if counter > oldValue { println("Newly Added Counter \(counter - oldValue)") } } 111

​Quick is really a powerful and intuitive programming language for macOS, iOS, watchOS and tvO...  


Read more
Read more
Similar to
Popular now
Just for you