In-depth iOS functional programming and responsive programming concepts

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 masonry && Snapkit source code has certain help.

Picture description

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

Masonry is a third-party framework for an OC-developed, very easy-to-use automatic layout; Snapkit is a swift version of the automated layout framework created by the masonry team; If you have not used it, the original or native version of the VFL language is used in the automatic layout, then I have to point "Great location!"

A typical masonry statement:

Make.centerY.equalTo (Self.view). offset (100); That's the "." Let 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

New Project Command +shift + N creates a person class and adds two methods to it:-(void) run; -(void) study; Simple implementation:

-(void) run{NSLog (@ "Run"); }-(void) Study {NSLog (@ "study")} to instantiate and invoke the associated method:

Person*person = [[Personalloc]init];  [Personrun]; [Personstudy]; The above three steps implement a very simple program.

Final goal:

Person.runblock (). Studyblock (). Runblock (); Person.studyblock (). Studyblock (). Runblock (); Decomposition target:

1. This method of invocation is implemented first:

[[Person run1] study1]; 2. Achieve the ultimate goal:

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]; To achieve the ultimate goal:

Person.runblock (). Studyblock (). Runblock (); In OC, the ' () ' block is executed in the form of (), assuming that if a block is returned, then I can use () 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:

Declaration-(person* (^) ()) Runblock; -(person* (^) ()) Studyblock; Implementation  -(person* (^) ()) Runblock {         person* (^block) () = ^ () {                              NSLog (@ "Run");                          return self;                };              return block; }  -(person* (^) ()) Studyblock {       person* (^block) () = ^ ()   {  & nbsp;                        NSLog (@ "study");               return self;               };         return block; And 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 (Attri     Bute,nslayoutrelationequal); }; }

Functional Programming Summary

If you want to call another method, you need to return an object, and if you want to execute it, you need to return a block, and if you want the returned block to invoke the object's method again, the block needs to return an object (that is, a block that returns an object).

The concept of responsive programming

Circulating on the Internet a very classic interpretation of the concept of "responsive Programming": In program development, 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.

In-depth iOS functional programming and responsive programming concepts