| layout | title | date | summary | categories |
|---|---|---|---|---|
post |
One Step Further: Swift Alternatives for Cpp-style for-in loop |
2016-04-11 |
Apple remove C-style for-loop, why don't we also remove Cpp-style for-in loop? |
functional |
As we all know, Apple decided to remove C-style for-loop from Swift. The most important reasons are that it is too old and not intuitive for the new programmers.
Since the programming languages is progressing, there is no explanation for not exploiting functional programming stuff in Swift. Instead of using Cpp-style for-in loop, we can do for-loop more Swifty, functional and better.
{% highlight swift %} var str = "Hello, playground"
//Converting a string into an array var arr = Array(str.characters) {% endhighlight %}
I wrote all of this code in playgrounds. I have also used their example.
{% highlight swift %} //Looping n times (0..<10).forEach({num in print(num)})
//old version for var i = 0, i < 10; i += 1{ print(i) } /* It prints from 0 to 10 exclusively to the console */ {% endhighlight %} Isn't it more intuitive!
{% highlight swift %} //Looping n time reverse (0..<10).reverse().forEach({number in print(number)})
(0..<10).reverse().forEach({print($0)})
//old version for var i = 10, i > 0; i -= 1{ print(i) } /* It prints from 10 to 0 exclusively to the console */ {% endhighlight %}
{% highlight swift %} //Looping with stride (0.stride(to: 10, by: 2)).forEach({print($0, terminator: " ")}) /* 0 2 4 6 8 */ {% endhighlight %}
{% highlight swift %} //Looping through array values //I want to print them in one line arr.forEach({char in print(char, terminator: " ")}) /* H e l l o , p l a y g r o u n d */ {% endhighlight %}
{% highlight swift %} //Reverse looping through array values arr.reverse().forEach({char in print(char, terminator: " ")}) /* d n u o r g y a l p , o l l e H */ {% endhighlight %}
{% highlight swift %} //Looping through an array with index arr.enumerate().forEach({(index,char) in print("(index):(char)", terminator: ";")}) /* 0:H;1:e;2:l;3:l;4:o;5:,;6: ;7:p;8:l;9:a;10:y;11:g;12:r;13:o;14:u;15:n;16:d; */ {% endhighlight %}
{% highlight swift %} //Looping through array indices arr.indices.forEach({index in print("i:(index)", terminator: " | ")}) /* i:0 | i:1 | i:2 | i:3 | i:4 | i:5 | i:6 | i:7 | i:8 | i:9 | i:10 | i:11 | i:12 | i:13 | i:14 | i:15 | i:16 | */ {% endhighlight %}
{% highlight swift %} var airports = ["YYZ": "Toronto Pearson", "DUB": "Dublin"]
//Looping through a dictonary airports.forEach({(key,value) in print("(key): (value)")}) /* DUB: Dublin YYZ: Toronto Pearson */ {% endhighlight %} Let's talk about iterating over a dictionary.
{% highlight swift %} //Looping through key in a dict airports.keys.forEach({(key) in print("(key)")}) /* DUB YYZ */ {% endhighlight %}
{% highlight swift %} //Looping through values in a dict airports.values.forEach({(value) in print("(value)")}) /* Dublin Toronto Pearson */ {% endhighlight %}
Happy coding!