Some useful array tips from Swift 4

preface

Swift provides two collection types to hold multiple values -- arrays (Array) and dictionaries (Dictionary). This we should all know, in the year before, bought Swift advanced (swift4.0), after the year is 1 little bit back learning, I have to say that meoshen wrote things are good, 69 yuan for the majority of programmers is not what. If you are interested in buying a book, really good

When I started learning arrays from the ground up, I found a number of functions that were really useful, so I won't go into more detail.

Mutable array technique in Swift 4.0

We can use Xcode to create playground as an exercise

First, create an array

let array = NSMutableArray(array: [1, 2, 3, 4 , 5, 6])

for in loops through

for x in array {
 print(x)
}

print

[

1 2 3 4 5 6

]

Do you want to iterate over the remaining elements minus the first element?

for x in array.dropFirst(){
 print(x)
}

print

[

2 3 4 5 6

]

dropFirst() function parameter is for x in ES50en. dropFirst(3) print :4 5 6.

Where there is first, there is almost always last

Want to iterate over elements other than the last three?

for x in array.dropLast(3){
 print(x)
}

print

[

1 2 3

]

Traversal with subscripts and array elements

for (num, element) in array.enumerated() {
 print(num, element)
}

Print left subscript right element

[

0 1
1 2
2 3
3 4
4 5
5 6

]

Left subscript and right element

conclusion