vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

codediodeio

import * as firebase from 'firebase/app';
import 'firebase/firestore';

var firebaseConfig = {
  // your firebase credentials
};


  // Initialize Firebase
firebase.initializeApp(firebaseConfig);

joepie91

Don't use VPN services.

No, seriously, don't. You're probably reading this because you've asked what VPN service to use, and this is the answer.

Note: The content in this post does not apply to using VPN for their intended purpose; that is, as a virtual private (internal) network. It only applies to using it as a glorified proxy, which is what every third-party "VPN provider" does.

• A Russian translation of this article can be found here, contributed by Timur Demin.
• A Turkish translation can be found here, contributed by agyild.
• There's also this article about VPN services, which is honestly better written (and has more cat pictures!) than my article.

lawloretienne

Table Of Contents

• Data Structures
  • Linked Lists
  • Trees
    • Binary Trees
    • Binary Search Tree
    • Red-Black Tree
    • AVL Tree
• Tries

gonzalezreal

iOS Cell Registration & Reusing with Swift Protocol Extensions and Generics

A common task when developing iOS apps is to register custom cell subclasses for both UITableView and UICollectionView. Well, that is if you don’t use Storyboards, of course.

Both UITableView and UICollectionView offer a similar API to register custom cell classes:

public func registerClass(cellClass: AnyClass?, forCellWithReuseIdentifier identifier: String)
public func registerNib(nib: UINib?, forCellWithReuseIdentifier identifier: String)

statickidz

---
METHOD 1

This should roughly sort the items on distance in MySQL, and should work in SQLite.
If you need to sort them preciser, you could try using the Pythagorean theorem (a^2 + b^2 = c^2) to get the exact distance.
---
SELECT *
FROM table
ORDER BY ((lat-$user_lat)*(lat-$user_lat)) + ((lng - $user_lng)*(lng - $user_lng)) ASC

snikch

- (UIViewController *)topViewController{
  return [self topViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
}

- (UIViewController *)topViewController:(UIViewController *)rootViewController
{
  if (rootViewController.presentedViewController == nil) {
    return rootViewController;
  }
  

jochenschoellig

import UIKit


class ChatCollectionViewFlowLayout: UICollectionViewFlowLayout {
    
    private var topMostVisibleItem    =  Int.max
    private var bottomMostVisibleItem = -Int.max
    
    private var offset: CGFloat = 0.0
    private var visibleAttributes: [UICollectionViewLayoutAttributes]?

webserveis

Material text sizes XML for Android

Simple helper file for standard text sizes in material design. The sizes are provided by the material design documentation https://www.google.com/design/spec/style/typography.html#typography-roboto

Standard Styles

Too many type sizes and styles at once can wreck any layout. A typographic scale is a limited set of type sizes that work well together, along with the layout grid. The basic set of styles are based on a typographic scale of 12, 14, 16, 20, and 34.

karntrehan

import android.os.Bundle
import android.view.View
import android.view.ViewGroup
import androidx.core.view.ViewCompat
import androidx.core.widget.NestedScrollView
import androidx.fragment.app.Fragment
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.fragment_data.nsvData
import kotlinx.android.synthetic.main.fragment_data.rvData