Swift function type

Functions can be used as a type, as a type without distinction from other data types:

There are 3 definitions of the following functions:

(1) Func Rectanglearea (width:double, height:double), Double {

Let area = width * height

Return area

}

(2) Func Trianglearea (bottom:double, height:double), Double {

Let area = 0.5 * Bottom * height

Return area

}

(3) Func SayHello () {

println ("Hello World")

}

The return type of the first and second functions is (double,double), Double, and the third function returns the type (), ()

The function is used as a parameter type: You can use the type of the function as the return type of another function:

Example:

Func Rectanglearea (width:double, height:double), Double {

Let area = width * height

Return area

}

Func Trianglearea (bottom:double, height:double), Double {

Let area = 0.5 * Bottom * height

Return area

}

Func Getarea (type:string)-(double,double)->double {

var returnfunction:(double,double) Double

Switch type {

Case "Rect":

Returnfunction = Rectanglearea

Case "Tria":

Return Trianglearea

Default

Returnfunction = Rectanglearea

}

Return returnfunction

}

var area = Getarea ("Tria")

println ("Trianglearea:\ (area (20,30))")

var area = Getarea ("rect")

println ("Trianglearea:\ (area (20,30))")

You can use function types as parameter types for other functions:

Example:

Func Rectanglearea (width:double, height:double), Double {

Let area = width * height

Return area

}

Func Trianglearea (bottom:double, height:double), Double {

Let area = 0.5 * Bottom * height

Return area

}

Func Getareabyfunc (funcName: (double,double), double, a:double,b:double), double {

var area = Funname (A, B)

Return area

}

var result:D ouble = Getareabyfunc (rectanglearea,20,30)

This article is from the "Ordinary Road" blog, please be sure to keep this source http://linjohn.blog.51cto.com/1026193/1620360

Swift function type