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Platform Language: Swift 5 SwiftPM compatible CocoaPods compatible Version License

This is a simple image crop library for iOS I made for fun on Christmas🎅 🎄 based on RxSwift,

which doesn't support customized resizing by users.

This would be appropriate when limiting crop rate control to users.




  • Swift 5

  • iOS 10.0 +

  • RxSwift 6.0

  • RxCocoa 6.0

  • RxGesture 4.0

  • SnapKit 5.0

  • Then 2.0



PhotoCropper is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'PhotoCropper'
$ pod install

Swift Package Manager(SPM)

In Xcode, add as Swift package with this URL:


  1. Import PhotoCropper on top of your view controller file.

  2. ⚠️ If you want to change the ratio or some configurations, you can change the values in viewDidLoad by the singleton instance called PhotoCropper "before you initialize the PhotoCropperView." For more information, please check the example files.

  3. Create a view using PhotoCropperView(with:) in a view controller.

  4. Make constraints of the PhotoCropperView you made in the view controller.

  5. Subscribe the resultImage: PublishSubject<UIImage?> in the PhotoCropperView you declared and when the subjec emits the result image, you can go with that.

  6. To change the ratio, use PhotoCropper.shared.ratio: BehaviorRelay<CGFloat> like below.

    • e.g. PhotoCropper.shared.ratio.accept(2 / 3)
    • 2 / 3 means 2:3 ratio of the size.
  7. Now you can crop the image using PhtoCropperView.crop: PublishSubject<Void>

    • To do this, you can bind a button or send a signal manually like this: PhotoCropoerVirw.crop.onNext(())



A singleton configuration instance.

⚠️ You should change the values before you initialize the view except the ratio and cornerRadius whose type is BehaviorRelay<CGFloat>.

You can change the valuse like this: PhotoCropper.shared.<PROPERTY_NAME>

/// The crop ratio
public var ratio: BehaviorRelay<CGFloat> { get }

/// Defines the `max zoom scale multiplier` by the `minZoomScale`
/// Default value is `5.0`
public var maxZoomScaleMultiplier: CGFloat

/// Hide grid
/// Default value is `false`
public var hideGrid: Boo

/// Hide frame border
/// Default value is `false`
public var hideFrameBorder: Bool

/// Hide the overlay views on the image
/// Default value is `false`
public var hideOverlay: Bool

/// Appearance
public var appearance: PhotoCropperAppearance

/// Defines the transition duration.
/// The default value is `0.25`
public var transitionDuration: CGFloat

/// Defines the animation duration.
/// The default value is `0.3`
public var animationDuration: CGFloat

/// Grid hide delay duration
/// - This defines the duration of when the grid will be hidden after user interaction done.
/// Default duration is `0.3`
public var gridHideDelayDuration: TimeInterval

/// Number of the grid lines
/// The number of the grid lines in the frame by each orientation.
/// Default duration is `3`
public var numberOfGridLines


Appearance configurations.

You can change the values from PhotoCropper singleton instance.


/// Corner radius of the frame.
/// Default value is `0`
public var cornerRadius: BehaviorRelay<CGFloat>

/// The color of `frame`.
/// Default value is `.white`
public var frameColor: UIColor

/// The color of `grid`.
/// Default value is `.white`
public var gridColor: UIColor

/// The color of the overlay for the image out of the frame.
/// Default value is `.black.withAlphaComponent(0.6)`
public var overlayColor: UIColor

/// The frame border width
/// Default value is `2.0`
public var frameBorderWidth: CGFloat

/// The grid width
/// Default value is `1.0`
public var gridWidth: CGFloat


To run the example project, clone the repo, and run pod install from the Example directory first.

//  ViewController.swift
//  PhotoCropper
//  Created by Aaron Lee on 12/26/2021.
//  Copyright (c) 2021 Aaron Lee. All rights reserved.

import UIKit
import RxCocoa
import RxGesture
import RxSwift
import SnapKit
import Then
import PhotoCropper

class ViewController: UIViewController {

  private var bag = DisposeBag()

  private var doneButton = UIBarButtonItem(barButtonSystemItem: .done,
                                           target: nil,
                                           action: nil)

  private var photoCropperView = PhotoCropperView(with: UIImage(named: "image"))

  private var stackView = UIStackView()
    .then {
      $0.axis = .vertical
      $0.spacing = 8
      $0.distribution = .fill
      $0.alignment = .fill

  private var orientationSegmentedControl = UISegmentedControl(
    items: { $0.rawValue }

  private var ratioSegmentedControl = UISegmentedControl(
    items: { $0.description(by: .landscape) }

  override func viewDidLoad() {



// MARK: - Configure

extension ViewController {

  private func configureView() {
    title = "PhotoCropper Example"
    navigationItem.rightBarButtonItem = doneButton

    if #available(iOS 13.0, *) {
      view.backgroundColor = .systemBackground
    } else {
      view.backgroundColor = .white


// MARK: - Layout

extension ViewController {

  private func layoutView() {


  private func layoutPhotoCropperView() {
    photoCropperView.snp.makeConstraints {

  private func layoutStackView() {

    stackView.snp.makeConstraints {

  private func layoutSegmentedControls() {
    [orientationSegmentedControl, ratioSegmentedControl].forEach {
      $0.selectedSegmentIndex = 0
      $0.snp.makeConstraints {


// MARK: - Bind

extension ViewController {

  private func bindRx() {


// MARK: - Input

extension ViewController {

  private func bindInput() {

  private func bindDoneButton() {
      .bind(to: photoCropperView.crop)
      .disposed(by: bag)

  private func bindOrientationSegmentedControlSelectedIndex(){
      .map { [weak self] index -> CGFloat in
        guard let self = self else { return 1 }
        let orientation = Orientation.allCases[index]
        let ratio = Ratio.allCases[self.ratioSegmentedControl.selectedSegmentIndex]
        let ratioValue = ratio.ratio(by: orientation)
        return ratioValue
      .bind(to: PhotoCropper.shared.ratio)
      .disposed(by: bag)

  private func bindRatioSegmentedControlSelectedIndex() {
      .map { [weak self] index -> CGFloat in
        guard let self = self else { return 1 }
        let orientation = Orientation.allCases[self.orientationSegmentedControl.selectedSegmentIndex]
        let ratio = Ratio.allCases[index]
        let ratioValue = ratio.ratio(by: orientation)
        return ratioValue
      .bind(to: PhotoCropper.shared.ratio)
      .disposed(by: bag)


// MARK: - Output

extension ViewController {

  private func bindOutput() {
      .subscribe(onNext: { [weak self] image in
        guard let self = self else { return }

        let vc = ResultImageViewController()
        vc.imageView.image = image
        self.navigationController?.pushViewController(vc, animated: true)
      .disposed(by: bag)



If you want to contribute to a project and make it better, your help is very welcome. Contributing is also a great way to learn more about social coding on Github, new technologies and and their ecosystems and how to make constructive, helpful bug reports, feature requests and the noblest of all contributions: a good, clean pull request.

Before you make a pull request.

We use swiftformat to clean up the codes.

  1. Instann swiftformat

    brew install swiftformat

  2. Run swiftformat . in the root directory of this projects.

  3. swiftformat --lint .

How to make a clean pull request

Look for a project's contribution instructions. If there are any, follow them.

  • Create a personal fork of the project on Github.
  • Clone the fork on your local machine. Your remote repo on Github is called origin.
  • Add the original repository as a remote called upstream.
  • If you created your fork a while ago be sure to pull upstream changes into your local repository.
  • Create a new branch to work on! Branch from develop if it exists, else from master.
  • Implement/fix your feature, comment your code.
  • Follow the code style of the project, including indentation.
  • If the project has tests run them!
  • Write or adapt tests as needed.
  • Add or change the documentation as needed.
  • Squash your commits into a single commit with git's interactive rebase. Create a new branch if necessary.
  • Push your branch to your fork on Github, the remote origin.
  • From your fork open a pull request in the correct branch. Target the project's develop branch if there is one, else go for master!
  • ...
  • Once the pull request is approved and merged you can pull the changes from upstream to your local repo and delete your extra branch(es).

And last but not least: Always write your commit messages in the present tense. Your commit message should describe what the commit, when applied, does to the code – not what you did to the code.


Aaron Lee,


PhotoCropper is available under the MIT license. See the LICENSE file for more info.


Simple image crop library for iOS







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