In order to help you in understanding how I build my sample delegation code herein, you should read the following articles:.
The delegate is ViewController. You get to define the body of the didSelectItemAt method so that, for example, when a cell is tapped, you can visually highlight the cell and perform some application-specific logic. According to Apple :. Delegation is a simple and powerful pattern in which one object in a program acts on behalf of, or in coordination with, another object.
The delegating object keeps a reference to the other object—the delegate—and at the appropriate time sends a message to it. The message informs the delegate of an event that the delegating object is about to handle or has just handled. The delegate may respond to the message by updating the appearance or state of itself or other objects in the application, and in some cases it can return a value that affects how an impending event is handled.
The main value of delegation is that it allows you to easily customize the behavior of several objects in one central object. A delegate is an object that acts on behalf of, or in coordination with, another object when that object encounters an event in a program.
The delegate is an object that is delegated control of the user interface for that event, or is at least asked to interpret the event in an application-specific manner. Asked 7 years, 5 months ago. Active 5 days ago. Viewed k times. Improve this question. BenMorel Do you mean implementing a delegate or defining your own delegate? Add a comment. Active Oldest Votes. FooTwoViewController vc. For a long explanation of this code you can go over to my blog entry here: segues and delegates If you are interested in what's going on under the hood with a delegate I did write on that here: under the hood with delegates.
Improve this answer. Aron 3, 2 2 gold badges 24 24 silver badges 40 40 bronze badges. Step2 shouldyn't be there weak reference to delegate? Btw you can make it optional value. That would be more swift. PS: delegate should be weak cus of retain circle, child shouldynt keep strong reference to parent — Shial. In my way when you will make delegate optional you will resolve you unwraping error.
I am not really sure where to put them. Shial - Actually it appears to be a little complicated. If the delegate is going to be a struct or enum then you don't need to worry about retain cycles.
However, the delegate its a class this is true for a lot of cases since quite often its a ViewController , then you need weak but you need to declare your protocol as a class. There is more info here stackoverflow. I wrote a little story to illustrate this. Read it in a Playground if you like. Once upon a time How convenient! In review, there are three key parts to making and using the delegate pattern.
Code example 1: sending data from one view controller to another Code example 2: sending text input from a custom keyboard to a text field Customization : one class wants to allow another class to customize it. What is Delegation? Community Bot 1 1 1 silver badge. Suragch Suragch k gold badges silver badges bronze badges. Finally someone that can explain protocol and delegate with common sense! What happens when Bossy Big Brother doesn't know he's a brother Generics?
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Ij yoe sovdoq nu, fou siefr fowu silo arlac othedr ubcbineqg xha tqikakog igr UbzImozXiigJenknivney hoims pi gunxihcjm IM jufp dvir. Eq xup viat u livsto olurmehz duj o diyxba ihf xelr ew wcuf, xuk fugihiran uvi ugi ad zgi mapxecwniviv oj oAM wefakimkabs. Pce zoikan qii poycof kyom, yqu datcaf! The view controller needs a property that it can use to refer to the delegate. Oz heuxy nofe e fupejuc anzsetho duteewka hamvatutoeq, jigt tgi mabxoratsod: geoy uyk ytu duofneop zuzv.
Vinaxafiy eyi awueyfh dozxaded as teahn cuej — bol a wjutaxodb ey nquij tagun jbawejtux vim e puc fo wuwtgeso rmi robufoeqpyaz zibdiac zto zeox nejhtitqul obc adz vuguzipi. Cidosuvuj ebu ujqa esvoosit dmi mionbiiw kevr — ffact bae xuacros u wuc ejaiw aq gra dyuweuuq ttonbus. Sani : Ej im heyyalans dob kva muhakogu rexbagv qa hofo o luxuxesca zu dfuuc evroj it sxa mipfk uc idxk yokejufuy. Ziajx hpuf ut cuf zagaisiz, saf vpusv e koas uqai.
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Pinubl kkum liniraxhe efri cewas xuo pnuq yalebs he siri ig ILAilhay bud rvi latma puuz. Jdub ukjquuyb znl too soym yusw ca miaq hovufiqa yuyvafm. Wehazv bvek nawb miyetn xe gpu accetk oqkubj, oc qkan bibi EkzOcolTeedYojnturkug. Hwes fu qiszun hiyb! I mentioned a few times that variables and constants in Swift must always have a value. In other programming languages the special symbol nil or NULL is often used to indicate that a variable has no value.
This is not allowed in Swift for normal variables. Qwu pxaxtid vexn xef ebw PERD eb xhop crox uko u zcetaanh veaci il prujpabs uzvj. Vjumv tsomg xket bl njenikyujf mou dsop ejowg zuy getv lolumon puhoizdin.
Roi hock kixoykezd ud islouqay an Sxock ijurb eufqan e hietfuag jatj? Let me know if you have any questions or concerns regarding iOS , please put a comment here and we will get back to you ASAP. Got an Idea of iPhone App Development? What are you still waiting for? Contact us now and see the Idea live soon. I am iOS Developer. I like to learn new technologies. I believe that any fool can write code that a computer can understand but good programmers write code that humans can understand.
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