IOS interview preparation - other articles

iOS Interview preparation - ios piece
ios Interview preparation - objective-c piece
ios Interview preparation - Online
IOS Interview preparation - C++ piece
iOS Interview preparation - Other articles

Design patterns

Factory mode
The singleton pattern
Builder pattern
Use multiple objects to make a step-by-step type . Become a simple object . The design pattern of type belongs to the creation pattern , It provides the best way to create objects
One Builder Class will construct the final object step by step . The Builder Class is independent of other objects .
Adapter pattern
As a bridge between two incompatible interfaces . This type of design pattern belongs to structural pattern , It combines the functions of two independent interfaces .
Chain responsibility mode
Usually each recipient contains a reference to another recipient . If a recipient cannot process the request , Then it will send the same transmission request as the next sender , And so on .
Observer mode
One to many mode , When an object is modified , Objects that depend on it are automatically notified .
MVC and MVVM Pattern
MVC Pattern - View - controller . Controller control mode and view .
MVVM view viewMode mode . call chaining

Algorithm

java Common functions

Introduce the toolkit

import java.util.*;

list Turn array

 String[] array2 = testList.toArray(new String[testList.size()]);

Array rotation list

ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(arrays));

Array copy

int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
int[] right = Arrays.copyOfRange(arr, middle, arr.length);

Quick sort

Objective-C Realization Quick sort ：
https://blog.csdn.net/htwhtw123/article/details/125347823?spm=1001.2014.3001.5501

data structure

Trees

Binary search tree （ Binary sort tree , Binary search tree ）
It could be an empty tree , Or a binary tree that has the following properties ： If its left subtree is not empty , Then the value of all nodes in the left subtree is less than the value of its root node ; If its right subtree is not empty , Then the value of all nodes in the right subtree is greater than the value of its root node ; Its left 、 The right subtree is also a binary sort tree .
AVL Trees （ Balance tree ）
A binary search tree , And the absolute value of the height difference between the left and right subtrees of each node （ Balance factor ） At most 1
The order of traversing the tree
The former sequence traversal Around the middle
In the sequence traversal Left middle right
Subsequent traversal Right and left

other

git Realization principle

Every time we run git add and git commit On command , Git The essential work is to save the rewritten file as a data object , Update the staging area , Record tree object , Finally, create a submission object that indicates the top-level tree object and the parent submission . These three main Git object —— Data objects 、 Tree object 、 Submit to —— Initially, they are kept in the form of separate files .git/objects Under the table of contents .
Git The core of is its object database , Which holds git The object of , The most important one is blob、tree and commit object ,blob Object realizes the recording of file content ,tree Object implements the file name 、 Record of file directory structure ,commit Object implements the version submission time 、 Version author 、 Version sequence 、 Records of additional information such as Version Description . These three types of objects , It's perfect git The basic function of ： Record of version status .
Git Reference refers to git object hash Pointer like file of key value . adopt Git quote , We can more easily locate the submission of a certain version .Git Branch 、tags And other functions are based on Git Reference to the implementation of .

UNIX Common commands

Instructions	meaning
cat	Display file contents
cd	Change the directory to the specified directory
ls	List the files under the current path
cp	Copy the source file to the destination
file	Determine the type of document
find	Find files
mkdir	Create directory
mv	Move （ rename ） file
pwd	Print current directory
rm	Delete file
rmdir	Delete folder
vim	open VIM Text editor
gzip	Compressed files .gz file
gunzip	Unzip the file

User mode switches to kernel mode

trigger
system call
interrupt
abnormal
technological process
User mode can directly read and write registers , User mode operation CPU, Save the state of the register to the corresponding memory , Then call the corresponding system function , Pass in the corresponding user stack PC Address and register information , Convenient for subsequent kernel method calls , Restore the user method execution site
take CPU The field of is changed to kernel mode , Write the code address corresponding to the kernel segment to PC In the register , Then start executing kernel methods , The corresponding method stack frame is saved in the kernel stack .
When the kernel method is executed , Will CPU The field of is changed to user status , Then use the previously written information to recover the execution of the user stack

frame

SDWebImage

https://www.jianshu.com/p/e5d583e81ac0

MLeakFinder

YYModel

Setting and getting the value of the attribute are both through objc_msgSend Function implementation