The realization of functional programming in-ios && the concept of responsive programming

Brief introduction

This article mainly reviews the --ios functional programming && responsive programming concept , how to realize the process of functional programming step-by-step, to read the Masonry && SnapKit source code has certain help.

Image matching

As an iOS developer, you must have used masnory/snapkit;

• Masonry is a third-party framework that is well-suited for automatic layout in OC development;
• Snapkit is a swift version of the automatic layout framework created by the masonry team;
  If you have not used the automatic layout in the original or native Apple version of the VFL language, then I have to give you a "praise"!

A typical masonry statement:

make.centerY.equalTo(self.view).offset(100);

That's the "." Let the masonry more vivid show to the developer, in my heart
Masnory/snapkit functional programming of a classic masterpiece, very worthy of reference and learning!

The benefits of chained programming do not have to say, used Masnory/snapkit know;

So the question is, how to write chained programming?

One-step implementation of a functional programming

1. New Project Command +shift + N
2. Create a Person class
   and add two methods to it

     (void)run;  - (void)study;

   Simple implementation:

     - (void)run{   NSLog(@"run");  }  - (void)study {   NSLog(@"study") }

3. Instantiate and invoke the associated method

   Person*person = [[Personalloc]init]; [personrun]; [personstudy];

   The above three steps to achieve a very simple program;

Final goal

    person.runBlock().studyBlock().runBlock();    person.studyBlock().studyBlock().runBlock();

Decomposition target
1. Implement this method first to call

      [[person run1] study1];

2. Achieve the ultimate goal again

Obviously, if you want to implement [person RUN1] to invoke a method, then run1 needs an object to return, allowing the object to invoke Study1.
After this analysis, it is simple to add a return value.

Code
Declaration of the method

-(Person*)run1;-(Person*)study1;

Implementation of the method

- (Person*)run1 {        NSLog(@"run");        return [[Personalloc] init];}- (Person*)study1{         NSLog(@"study"); return[[Personalloc]init];}

Achieve the ultimate goal:

    person.runBlock().studyBlock().runBlock();

In OC, the ' () ' block is () executed in the form of a, assuming that if a block is returned, then I can use it () to achieve the effect of runblock ().
Combined with our decomposition steps, Runblock () represents a block, and if the return value of the block is an object, then another method is called, so you can always link it down! Achieve the goal we want!

Code:
Statement

(Person* (^)())runBlock;- (Person* (^)())studyBlock;

Realize:

 - (Person* (^)())runBlock {         Person* (^block)() = ^() {                            NSLog(@"run");                          return self;                };              return block;} - (Person* (^)())studyBlock { Person* (^block)() = ^() { NSLog(@"study"); return self; }; return block;}

Let's take a look at a functional programming of masonry.

make.right.equalTo(self.right).insets(kPadding);

The function that is finally called:
Returned is a block with a return value of Masconstraint.

- (MASConstraint* (^)(id))equalTo {    return ^id(idattribute) {                     return self.equalToWithRelation(attribute,NSLayoutRelationEqual); };}

Functional Programming Summary

• If you want to call another method, you need to return an object;
• If you want to use () to execute, then need to return a block;
• If you want the returned block to invoke the object's method again, then the block needs to return an object (that is, a block that returns a value of one object).

The concept of responsive programming

Circulating on the Internet a very classic explanation of the ' responsive programming concept '
In the development of the program:
A = B + C
After the value of B or C changes after assignment, the value of a does not change.
Responsive programming, the goal is that if the value of B or C changes, the value of a will change at the same time;

Wen/ios audio and video (Jane book author)
Original link: http://www.jianshu.com/p/7017a220f34c
Copyright belongs to the author, please contact the author to obtain authorization, and Mark "book author".

The realization of functional programming in-ios && the concept of responsive programming