Enumerations
Enumerations are sets of symbolic names bound to unique, constant values, which can be compared by identity.
Enum Declaration​
Enums are declared using the enum keyword,
followed by the name of the enum, the raw type after a colon,
and the requirements, which must be enclosed in opening and closing braces.
The raw type must be an integer subtype, e.g. UInt8 or Int128.
Enum cases are declared using the case keyword,
followed by the name of the enum case.
Enum cases must be unique. Each enum case has a raw value, the index of the case in all cases.
The raw value of an enum case can be accessed through the rawValue field.
The enum cases can be accessed by using the name as a field on the enum,
or by using the enum constructor,
which requires providing the raw value as an argument.
The enum constructor returns the enum case with the given raw value,
if any, or nil if no such case exists.
Enum cases can be compared using the equality operators == and !=.
_36// Declare an enum named `Color` which has the raw value type `UInt8`,_36// and declare three enum cases: `red`, `green`, and `blue`_36//_36access(all)_36enum Color: UInt8 {_36_36 access(all)_36 case red_36_36 access(all)_36 case green_36 _36 access(all)_36 case blue_36}_36// Declare a variable which has the enum type `Color` and initialize_36// it to the enum case `blue` of the enum_36let blue: Color = Color.blue_36// Get the raw value of the enum case `blue`._36// As it is the third case, so it has index 2_36//_36blue.rawValue // is `2`_36// Get the `green` enum case of the enum `Color` by using the enum_36// constructor and providing the raw value of the enum case `green`, 1,_36// as the enum case `green` is the second case, so it has index 1_36//_36let green: Color? = Color(rawValue: 1) // is `Color.green`_36// Get the enum case of the enum `Color` that has the raw value 5._36// As there are only three cases, the maximum raw value / index is 2._36//_36let nothing = Color(rawValue: 5) // is `nil`_36// Enum cases can be compared_36Color.red == Color.red // is `true`_36Color(rawValue: 1) == Color.green // is `true`_36// Different enum cases are not the same_36Color.red != Color.blue // is `true`