Swift Learning Notes (22)--basic operation of the dictionary

(1) Calculating the dictionary length

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(2) Infer if the dictionary is empty

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(3) Querying dictionary elements

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(4) Remove the dictionary elements for stitching

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(5) Insert a key value pair in the dictionary

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(6) Dictionary changes a key value pair

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(7) Usage Update element values

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In fact the above method is another return value:

(8) Remove an element from the dictionary

Use the function Removevalueforkey () to remove a value from the dictionary:

Same. Removevalueforkey () will also have a return value:

(9) Traversing a dictionary

(10) The keys or values of the dictionary are traversed separately

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Swift Learning Notes (22)--basic operation of the dictionary