genkernel

+ (UIImage *)thumbnailImageFromURL:(NSURL*)imageUrl downsampledToMaxPixelSize:(NSNumber *)maxPixelSize {
	NSDictionary *opts = @{
		(id)kCGImageSourceThumbnailMaxPixelSize: maxPixelSize,
		(id)kCGImageSourceCreateThumbnailWithTransform: (id)kCFBooleanTrue,
		(id)kCGImageSourceCreateThumbnailFromImageIfAbsent: (id)kCFBooleanTrue
	};
	CGImageSourceRef src = CGImageSourceCreateWithURL((__bridge CFURLRef)imageUrl, NULL);
	CGImageRef thumbnail = CGImageSourceCreateThumbnailAtIndex(src, 0, (__bridge CFDictionaryRef)opts);
	
	UIImage *img = [UIImage imageWithCGImage:thumbnail];

genkernel

+ (instancetype)sharedInstance {
	static id instance = nil;
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
		instance = self.new;
	});
	return instance;
}

genkernel

#sudo vim /Library/LaunchDaemons/io.redis.redis-server.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Label</key>
	<string>io.redis.redis-server</string>
	<key>ProgramArguments</key>
	<array>

genkernel

struct User: Decodable {
	let username: String
	let email: String
	
	let accountType: AccountType
	
	let rank: Int
	let badges: [Badge]
}

genkernel

private struct InputUser: Decodable {
	var email: String
	var password: String
}

private struct InputUserContract: ModelContract {
 	typealias M = InputUser
		
 	let email: PropertyPolicy = (\M.email, EmailValidator()))
 	let password: PropertyPolicy = (\M.password, StringValidator(length: (min: 8, max: 20)))

genkernel

class LoginViewController_ByExample: UIViewController {

	private var user = InputUser(email: "", password: "")
	private let userContract = InputUserContract()
	private let formValidator = ModelValidator()

	// MARK: - UITextFieldDelegate
	
	func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
		let delayed = {