Swift Learning Notes (24)--constant array and constant dictionary __swift

As with other data types in swift, arrays and dictionaries can be defined separately as Var,let, which is variables and constants. Arrays and dictionaries that are defined as let constants are immutable. Here's a quick look:

Import Uikit let

courses_dict = [1: "Advanced Mathematics", 2: "College English", 3: "Program Design"]  //constant let

Course_array = ["Advanced mathematics", "College English", "Program Design") "]   //Constant

Courses_dict.removevalueforkey (3)    //error, cannot delete
courses_dict.updatevalue (" level 46 ", Forkey:2)  //error, cannot modify
courses_dict[4] = "level 46"    //error, cannot insert


course_array.removeatindex (0)  //error, cannot delete
COURSE_ARRAY[1] = "level 46"   //error, cannot modify
course_array[3] = "linear algebra"  //error, cannot insert

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