9. Swift

  • 9.1. Swift tutorial

    Swift, an open source programming language that supports multiple programming paradigms and compilation, was released by ...
    2025-10-25 13:33:47 UTC
  • 9.2. Swift environment building

    Swift is an open source programming language for developing OS X and iOS applications. Before the formal development of ap...
    2025-10-25 13:33:51 UTC
  • 9.3. Swift basic syntax

    In the previous chapter, we talked about how to create “Hello, World!” in the Swift language. program. Now let’s review. I...
    2025-10-25 13:33:47 UTC
  • 9.4. Swift data type

    When we program in any programming language, we need to use a variety of data types to store different information. The da...
    2025-10-25 13:33:50 UTC
  • 9.5. Swift variable

    A variable is an easy-to-use placeholder that refers to the computer’s memory address. Each variable in Swift specifies a ...
    2025-10-25 13:33:49 UTC
  • 9.6. Swift optional type

    The optional (Optional) type of Swift, which is used to handle cases where values are missing. Optional means “there is a va...
    2025-10-25 13:33:50 UTC
  • 9.7. Swift constant

    Once a constant is set, its value cannot be changed while the program is running. Constants can be any data type such as i...
    2025-10-25 13:33:47 UTC
  • 9.9. Swift operator

    An operator is a symbol that tells the compiler to perform a mathematical orlogical operation. Swift provides the followin...
    2025-10-25 13:33:51 UTC
  • 9.10. Swift conditional statement

    A conditional statement executes the program through one or more conditions set, executing the specified statement when the ...
    2025-10-25 13:33:45 UTC
  • 9.11. Swift if statement

    One if a statement consists of a Boolean expression followed by one or more statements. 9.11.1. Grammar # In Sw...
    2025-10-25 13:33:45 UTC
  • 9.12. Swift if…else statement

    One if statement can be followed by an optional else statement else statement in a Boolean expression false ...
    2025-10-25 13:33:48 UTC
  • 9.13. Swift if…else if…else statement

    One if statement can be followed by an optional else if...else statement else if...else statement is use...
    2025-10-25 13:33:46 UTC
  • 9.14. Swift nested if statement

    In the Swift language, you can use a if or else if use another within the statement if or else if statem...
    2025-10-25 13:33:50 UTC
  • 9.15. Swift switch statement

    The switch statement allows you to test when a variable is equal to multiplevalues. In the Swift language, as long as the ma...
    2025-10-25 13:33:47 UTC
  • 9.16. Swift cycle

    Sometimes, we may need to execute the same piece of code multiple times. In general, statements are executed sequentially: t...
    2025-10-25 13:33:49 UTC
  • 9.17. Swift for-in cycle

    Swift for-in loops are used to traverse all the elements in a collection, such as intervals represented by numbers, elem...
    2025-10-25 13:33:51 UTC
《地理信息系统原理、技术与方法》  97

最近几年来,地理信息系统无论是在理论上还是应用上都处在一个飞速发展的阶段。 GIS被应用于多个领域的建模和决策支持,如城市管理、区划、环境整治等等,地理信息成为信息时代重要的组成部分之一; “数字地球”概念的提出,更进一步推动了作为其技术支撑的GIS的发展。 与此同时,一些学者致力于相关的理论研究,如空间感知、空间数据误差、空间关系的形式化等等。 这恰好说明了地理信息系统作为应用技术和学科的两个方面,并且这两个方面构成了相互促进的发展过程。