Programmer Group

Knowledge preparation First of all, we need to know a scenario. We click on the application on the screen, and then we can see that the application is fully displayed and can be operated. In this process, the system, runtime and our own code have done a lot of work, and many excellent blogs have descr ...

Introduction In the development of iOS App, we need to encrypt the account, password and other personal private information to ensure the security of user information. Then these private information can be saved in the keychain, because the invisibility of the keychain can ensure the security of the u ...

I have a dictionary. I need to use dictionary to generate a JSON string. Can it be converted? Can you help me? #1 building This is the category for NSArray and NSDictionary, which makes this operation very easy. I added an option for beautiful printing (line breaks and labels make reading easier). @interface NSDictionary (BVJSONString) ...

Today, let's briefly introduce the use of kotlin for cross platform development, so that one code, multiple runs. I. Introduction First of all, I extracted some basic information from official documents. At the beginning of design, kotlin language has a clear goal, that is, it can be used on all plat ...

Title Solution Meaning: a row of n level 1 heroes will upgrade their experience of fighting monsters. They will tell you the experience value required by each level. If you can't upgrade the experience value, you will be given two operations: W l r e for each wave of monsters, send heroes in the [l, ...

Similar digital advanced set jw big guy's: set the naked question. First, each array is de duplicated and then thrown into the set. The answer is the number of elements reduced after de duplication / the number of elements in the set. You can use unique for de duplication. However, this problem feels ...

A - Neon Sign Meaning: the complete graph of n points. The colors of each vertex and other vertex edges are blue and red. The number of triangles with the same color on three sides is required. Considering that violence O(n^3) can T, so I tried to find a counter solution (if the colors on both sides a ...

The best location of book information table based on chain storage structure describe   Define a linked list containing book information (book number, book name, price), read in the corresponding book data to complete the creation of the book information table, and then search for the books in the ...

Problem surface Given N points, let's draw the smallest circle that contains all the points. Analysis This problem is actually to find out a circle determined by three points, which can contain all other points. There is a close relationship with three points in a circle. First, three points in a ci ...

In order to provide a good interactive effect for users, many app s usually add animation effect to achieve the goal. A good animation effect will often play the role of masterstroke. Today, we will realize the water wave animation in IOS. First on the renderings: It's a little complicated to see many effects of realizing w ...