I saw a dictionary data, its value is like:
var myDict = ["name": "John",
"age": 28]
I see a code like below:
myDict.flatMap {
let a = $0.0
let b = $0.1
...
}
What does $0.0
mean? What does $0.1
mean? What is the difference between $0
and $0.1
?
$0
is a shorthand name for first argument passed to closure. In this case, as you're mapping a Dictionary
, that argument is a tuple - hence $0.0
is a key, and $0.1
is a value
For more info on shorthand argument names, see Swift documentation on closures
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