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What is the difference between 1:calayer and UIView?

The biggest difference between the two is that the coating does not render directly to the screen;

UIView is the basis of the iOS interface elements, all interface elements are inherited from it, and his own is entirely by the coreanimation to achieve;

The real drawing part is the Calayer class to manage;

A uiview can have n calayer, each layer to display a kind of thing, enhance the uiview ability.

2:gcd

GCD is a newer multi-core programming solution developed by Apple.

GCD is an efficient and powerful alternative to technologies such as Nsthread, and can handle complex asynchronous programming issues such as data locking and resource leaks.

3:TCP and UDP

TCP: (Transmission Control Protocol), providing connection-oriented, reliable location-to-point communication;

UDP: (User Datagram Protocol), providing non-connected unreliable point-to-multipoint communication;

In the actual application, look at the procedure to pay attention to which aspect is reliable or fast;

4:socket connection to HTTP connection

HTTP connection: Short connection. That is, the client sends a request to the server, and after the server responds, the link is broken;

Socket connection: Long connection. That is, once the client is established with the server, it will not be actively broken down.

5:TCP Three-time handshake

First handshake: The client sends a SYN (SYN=J) packet to the server and enters the Syn_send state, waiting for the server to confirm;

Second handshake: The server receives the client's SYN packet, must confirm the customer's SYN (ack = j + 1), and also send itself a SYN packet (syn = k), that is, the SYN + ACK packet, when the server enters the SYN_RECV state;

Third handshake: After the customer receives the Syn+ack packet sent by the server, sends a confirmation packet (ACK = k + 1) to the server, the packet is sent, the client and server enter the established state, and the third handshake is completed.

What are the communication methods between objects in 6:ios?

Agent Block Notification KVO

Features of the 7:http protocol, GET POST request, and HTTPS protocol

HTTP short connection, the client actively send the request, the server responds, the server corresponding, the connection disconnects. The GET request has no request body, and the POST request has a request body.

HTTPS: Secure Hypertext Transfer Protocol. Based on HTTP development, users exchange information between the client computer and the server. It uses Secure Sockets Layer (SSL) for information exchange, which is simply the security version of HTTP.

8:xml and JSON data parsing

Xml:dom and Sax parsing

Dom parsing must complete the construction of the DOM tree, which is good for memory and resource-intensive when dealing with large XML files.

Sax parsing is an event-driven model that, when parsing XML, begins or ends a tag, attribute, or instruction with an XML, and the program generates a corresponding event to handle accordingly. Sax is better for working with larger documents than DOM.

Json:jsonkit, System comes with

9:tableview Reuse Design Pattern

UIButton design mode of single case combinatorial design mode

10: Data storage

Preferences plist file SQLite database coredate

11: How does the breakpoint continue to be transmitted?

12:core content: Coreanimation, Coregraphics, respectively, using the CA or CG to do what kind of animation or image content?

13:nsoperationqueue, GCD

14: Algorithm: Bubble sort, dichotomy, data structure (linked list, binary tree, algorithm time complexity, space complexity), operating system, network knowledge.

Advanced iOS Development Engineer's face test