oguzhanvarsak

Interview Questions for iOS Developers

1. Classes vs structs

In Swift, structs are value types whereas classes are reference types. When you copy a struct, you end up with two unique copies of the data. When you copy a class, you end up with two references to one instance of the data. It’s a crucial difference, and it affects your choice between classes or structs. (+ Class extendable, struct does not.)

2. What’s the difference between var and let? Which one would you choose for properties in a struct and why?

Both let and var are for creating variables in Swift. let helps you create immutable variables (constants) while on the other hand var creates mutable variables.

3. What does the mutating keyword mean?

The mutating keyword lets callers know that the method is going to make the value change.

nitin-agam

import UIKit

infix operator |: AdditionPrecedence
public extension UIColor {
    
    struct App {
        static let hyperLink = UIColor.colorWithHex(hex: "#FFFFFF")
        static let background = UIColor.white | UIColor.black
    }
    

PaulWall43

func createThumbnailOfVideoFromRemoteUrl(url: String) -> UIImage? {
    let asset = AVAsset(url: URL(string: url)!)
    let assetImgGenerate = AVAssetImageGenerator(asset: asset)
    assetImgGenerate.appliesPreferredTrackTransform = true
    //Can set this to improve performance if target size is known before hand
    //assetImgGenerate.maximumSize = CGSize(width,height)
    let time = CMTimeMakeWithSeconds(1.0, 600)
    do {
        let img = try assetImgGenerate.copyCGImage(at: time, actualTime: nil)
        let thumbnail = UIImage(cgImage: img)

mansi-27

extension UIView {
    /// Sets border to the UIView
    func setViewBorder(withWidth width: CGFloat = 1.0, color: UIColor) {
        self.layer.borderWidth = width
        self.layer.borderColor = color.cgColor
    }
    
}

mansi-27

extension UIView {
    
    /// Produce vertical shake animation
    func shakeVertically(withCount count: Float = 4, duration: TimeInterval = 0.3, translation: Float = -10) {
        
        let animation: CABasicAnimation = CABasicAnimation(keyPath: "transform.translation.y")
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
        animation.repeatCount = count
        animation.duration = (duration)/TimeInterval(animation.repeatCount)
        animation.autoreverses = true

mansi-27

extension UIView {
    
    /// Sets rounded corners to the UIView
    func roundedCorners(radius: CGFloat? = nil) {
        if let radius = radius {
            layer.cornerRadius = radius
        } else {
            layer.cornerRadius = frame.size.height / 2
        }
        clipsToBounds = true

mansi-27

extension UIView {
    
    /// Produce horizontal shake animation
    func shakeHorizontally(withCount count: Float = 4, duration: TimeInterval = 0.3, translation: Float = -10) {
        
        let animation: CABasicAnimation = CABasicAnimation(keyPath: "transform.translation.x")
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
        animation.repeatCount = count
        animation.duration = (duration)/TimeInterval(animation.repeatCount)
        animation.autoreverses = true

mxcl

extension UIImage {
    func blurred(radius: CGFloat) -> UIImage {
        let ciContext = CIContext(options: nil)
        guard let cgImage = cgImage else { return self }
        let inputImage = CIImage(cgImage: cgImage)
        guard let ciFilter = CIFilter(name: "CIGaussianBlur") else { return self }
        ciFilter.setValue(inputImage, forKey: kCIInputImageKey)
        ciFilter.setValue(radius, forKey: "inputRadius")
        guard let resultImage = ciFilter.value(forKey: kCIOutputImageKey) as? CIImage else { return self }

albertbori

//
//  StandardTooltip.swift
//
//  Created by Albert Bori on 11/20/17.
//

import Foundation

@objc
class StandardTooltip: NSObject {

eleev

 func getURL(ofPhotoWith mPhasset: PHAsset, completionHandler : @escaping ((_ responseURL : URL?) -> Void)) {
        
        if mPhasset.mediaType == .image {
            let options: PHContentEditingInputRequestOptions = PHContentEditingInputRequestOptions()
            options.canHandleAdjustmentData = {(adjustmeta: PHAdjustmentData) -> Bool in
                return true
            }
            mPhasset.requestContentEditingInput(with: options, completionHandler: { (contentEditingInput, info) in
                completionHandler(contentEditingInput!.fullSizeImageURL)
            })