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iOS Swift 2.0 Collections and Control Flow Dictionaries Recap: Dictionaries

Minh Pham
Minh Pham
724 Points
Posted by Minh Pham
Minh Pham
724 Points

What is wrong with these two lines of code?

I think these two lines of code are equivalent, but the answer is no.

dict.updateValue("yetAnotherValue", forKey: 3)

dict[3] = "yetAnotherValue"

Can someone explain me why?

1 Answer

Damien Watson
Damien Watson
27,419 Points
Damien Watson
Damien Watson
27,419 Points

Hi Minh,

I believe that the first is replacing a value for the key === 3, where the second is replacing the item at the '3' index of the array.

var dict = [2:"abc",
    3:"def",
    4:"ghi",
    0:"jkl"
]

// Replace key of 3
dict.updateValue("yetAnotherValue", forKey: 3)
/*
dict = [2:"abc",
    3:"yetAnotherValue",
    4:"ghi",
    0:"jkl"
]
*/

// Replace index 3
dict[3] = "yetAnotherValue"
/*
dict = [2:"abc",
    3:"def",
    4:"ghi",
    0:"yetAnotherValue"
]
*/
kisu kim
kisu kim
11,691 Points
kisu kim
kisu kim
11,691 Points

You must be confused between the dicitionary and the array syntax.