swift--Introduction

Swift is the development language that Apple released on June 2, 2014, starting with XCODE6 to support the Swift language

is a strongly typed language, where the strong type contains two meanings: 1 All variables must be declared and used, and 2 of variables of the specified type can only accept values that match the type. Strongly typed languages can detect source code errors during compilation, thus ensuring a more robust program

is an object-oriented, compiler-based language

Swift does not require a semicolon at the end of each execution statement

Swift also supports process-oriented programming with the same class and method levels

Swift Program Entry

There are two scenarios: 1 only one source program 2 has multiple source programs

1 when a swift application has only one source program, the first executable code of the file is the portal of the SWIFT program.

2 When Swift application has many source programs, only the source program with file name Main.swift can place executable code, the first line of executable code is the portal of Swift program, other source program can only define classes and functions, etc.

Use the terminal window to compile and run the SWIFT program

Create a Helloworld.swift file and compile it in the terminal program

Swiftc-o Hello.out Helloworld.swift

Hello.out is the compilation of the generated file, which is an executable file

Run the executable file

./hello.out

Which./is to tell the system in the current

If you want to compile multiple source programs into a single file

Swiftc-o hello.out Test.swift Main.swift

Comment Method

Single-line Comment

Comment Content

Multi-line comments

/*

Comment Content

Comment Content

*/

Separator

1 semicolon;

Swift does not require each statement to end with a semicolon, but it can also do so

Swift Each statement can be cross-line, the calling function can cross the line, the call property can not cross the line

When there are more than one statement in a row, you need to separate them with semicolons

2 curly Braces {}

Define a block of code, such as classes, structs, enumerations, functions

3 square brackets []

Used to access arrays and dictionaries, to set the index of an array element that you want to access or a key for a dictionary element

4 parenthesis ()

When defining a function, parentheses are used to include all formal parameter declarations, and the function must be called with parentheses to pass in the parameter values

5 spaces

Spaces can appear anywhere in the SWIFT program

6 dots.

A dot is usually used as a class, struct, enumeration, instance to invoke a property or method

Naming rules

Swift language case-sensitive

Cannot start with a number

Composed of characters, numbers, underscores, and $

swift--Introduction