Common Swift data types

value type	enum	Optional
structure (Struct)	Bool, Int, Float, Double, Character
	String, Array, Dictionary, Set
reference type	class	class

Swift flow control

• The () after the flow control if, while, for in Swift can be omitted, and the brace after the condition cannot be omitted
• Starting from Swift3, the increment and decrement operators are removed
• repeat-while is equivalent to do-while in C language

if-else

while

for

Sw The use of ift’s for loop is combined with the interval type. Interval type in Swift

< p>for loop use

If the variable i is not used in the for loop body, you can use _omit

The interval operator is used on the array for loop traversal

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