9. Swift

  • Swift, an open source programming language that supports multiple programming paradigms and compilation, was...
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  • Swift is an open source programming language for developing OS X and iOS applications. Before the formal deve...
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  • In the previous chapter, we talked about how to create “Hello, World!” in the Swift language. program. Now let’s revie...
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  • When we program in any programming language, we need to use a variety of data types to store different information. ...
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  • A variable is an easy-to-use placeholder that refers to the computer’s memory address. Each variable in Swift...
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  • The optional (Optional) type of Swift, which is used to handle cases where values are missing. Optional means “there i...
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  • Once a constant is set, its value cannot be changed while the program is running. Constants can be any data t...
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  • A literal quantity is a value such as a specific number, string, or Boolean value that can directly indicate its own t...
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  • An operator is a symbol that tells the compiler to perform a mathematical orlogical operation. Swift provides...
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  • A conditional statement executes the program through one or more conditions set, executing the specified statement whe...
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  • One if a statement consists of a Boolean expression followed by one or more statements. ...
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  • One if statement can be followed by an optional else statement ...
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  • One if statement can be followed by an optional else if...
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  • In the Swift language, you can use a if or else if ...
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  • The switch statement allows you to test when a variable is equal to multiplevalues. In the Swift language, as long as ...
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  • Sometimes, we may need to execute the same piece of code multiple times. In general, statements are executed sequentia...
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  • Swift for-in loops are used to traverse all the elements in a collection, such as intervals ...
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  • This loop has been deprecated in Swift 3. Swift for a loop is used to repeat a seri...
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  • Swift while the loop begins by calculating a single condition. If the condition is ...
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  • Swift repeat...while the cycle is not like for and w...
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  • Swift continue statement tells a loop body to stop this loop iteration immediately and resta...
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  • Swift break statement immediately ends the execution of the entire control flow. If...
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  • Swift fallthrough statement let case subsequent statements continu...
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  • A Swift string is a collection of characters. For example, “Hello, World!”a collection of values of such an ordered ch...
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  • The character of Swift is a single character string literal, and the data type is Character ...
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  • Swift arrays use ordered lists to store multiple values of the same type. The same value can appear multiple times in ...
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  • Swift dictionaries are used to store unordered collections of data of the same type. Swift dictionaries force the type...
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  • A separate block of code that the Swift function uses to accomplish a specific task. Swift uses a unified syn...
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  • Closures are self-contained blocks of functional code that can beused in code or used as parameters to pass values. ...
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  • Enumeration is simply a data type, except that this data type contains only custom-specific data, which is a collectio...
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  • The Swift structure is a general and flexible construct used to build code. We can extend the function of the...
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  • The Swift class is a generic and flexible construct used to build code. We can define properties (constants, ...
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  • The Swift property associates a value with a specific class, structure, or enumeration. Attributes can be div...
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  • Swift methods are functions associated with certain types In Objective-C, a class is the only type that can d...
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  • Inheritance can be understood as one class getting the methods and properties of another class. When a class ...
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  • The construction process is a preparation process for using an instance of aclass, structure, or enumerated type. This...
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  • The destructor is called immediately before an instance of a class is released. Use keywords deinit ...
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  • An optional chain is a process that can request and invoke properties, methods, and subscripts, and the target for a r...
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  • Swift uses automatic reference counting (ARC) to track and manage application memory Usually we don’t need to...
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  • Swift language type conversion can determine the type of instance. It can also be used to detect whether an instance t...
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Principles, Technologies, and Methods of Geographic Information Systems  102

In recent years, Geographic Information Systems (GIS) have undergone rapid development in both theoretical and practical dimensions. GIS has been widely applied for modeling and decision-making support across various fields such as urban management, regional planning, and environmental remediation, establishing geographic information as a vital component of the information era. The introduction of the “Digital Earth” concept has further accelerated the advancement of GIS, which serves as its technical foundation. Concurrently, scholars have been dedicated to theoretical research in areas like spatial cognition, spatial data uncertainty, and the formalization of spatial relationships. This reflects the dual nature of GIS as both an applied technology and an academic discipline, with the two aspects forming a mutually reinforcing cycle of progress.