soapyigu

// Convention: using GCD and URLSession
import Foundation
import UIKit

enum NetworkError: Error {
    case invalidURL
    case noData
    case failedRequest
    case returnedError
}

soapyigu

class NotificationCenter {
    static let shared = NotificationCenter()
    
    // notification to (class name and closures)
    private var notificationsStorage = [String: [(String: [(String, Any) -> Void)]]]()
    
    private init() { }
    
    func addObserver(_ class: Any?, name: String, closure: @escaping (String, Any) -> Void) { }
    

soapyigu

// https://stackoverflow.com/questions/26028918/how-to-determine-the-current-iphone-device-model

import SystemConfiguration
import UIKit

public extension UIDevice {
  static let modelName: String = {
    var systemInfo = utsname()
    uname(&systemInfo)
    let machineMirror = Mirror(reflecting: systemInfo.machine)

soapyigu

// https://stackoverflow.com/questions/26028918/how-to-determine-the-current-iphone-device-model

func machineName() -> String {
  var systemInfo = utsname()
  uname(&systemInfo)
  let machineMirror = Mirror(reflecting: systemInfo.machine)
  return machineMirror.children.reduce("") { identifier, element in
    guard let value = element.value as? Int8, value != 0 else { return identifier }
    return identifier + String(UnicodeScalar(UInt8(value)))
  }

soapyigu

#import <FBRetainCycleDetector/FBRetainCycleDetector.h>

self.block = ^{
    NSLog(@"%@", self);
};

FBRetainCycleDetector *detector = [FBRetainCycleDetector new];
[detector addCandidate:self];
NSSet *retainCycles = [detector findRetainCycles];
NSLog(@"%@", retainCycles);

soapyigu

@interface ViewController ()

@property (nonatomic, copy) void (^block)(void);

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

soapyigu

BEGIN:VCALENDAR

VERSION:2.0

BEGIN:VEVENT
SUMMARY: [A] 🇷🇺Russia vs. 🇸🇦Saudi Arabia
DTSTART;TZID=America/Los_Angeles:20180614T080000
DTEND;TZID=America/Los_Angeles:20180614T094500
END:VEVENT

soapyigu

@interface Queue<__covariant ObjectType> : NSObject

- (void)enqueue:(ObjectType)value;
- (ObjectType)dequeue;

@end

soapyigu

int main(int argc, const char * argv[]) {
    @autoreleasepool {
      
        Queue<Sub *> *subQueue = [[Queue alloc] init];
        Queue<Sup *> *supQueue = subQueue; // Warning: Incompatible pointer types initializing 'Queue<Base *>' with an expression of type 'Queue<Sub *>'
        
        [supQueue enqueue:[Sub new]];
    }
  
    return 0;

soapyigu

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        Queue<NSString *> *stringQueue = [[Queue alloc] init];
        [stringQueue enqueue:@"abc"]
        
        Queue<NSNumber *> *numberQueue = [[Queue alloc] init];
        [numberQueue enqueue:@123];
        
        [numberQueue enqueue:@"abc"];		// Warning: Incompatible pointer types sending 'NSString *' to parameter of type 'NSNumber *'