CODEWITHSUNDEEP
iosobjective-cxcodeuinavigationcontrollerpresentmodalviewcontroller
9to5ios
9to5ios

Reputation: 5545

presentModalViewController vs pushviewcontroller memory cosumption

I have two method to jump from one viewcontroller to another

For presentViewController

  [self presentModalViewController:view animated:YES];

For pushViewControlle should use

[self.navigationController pushViewController:view animated:YES];

Which Will be best approach ?

Which will cause more memory leak?

Which one is use if Our Design is like

Introduction view (bunch of slides )-> login -> signUp-> HomeActivityScreen-> Then Bunch of tab bar in it

Upvotes: 1

Views: 8534

Answers (3)

Duyen-Hoa
Duyen-Hoa

Reputation: 15784

They are two approaches to navigate from one view controller to other view controller.

By default: - pushviewcontroller: you will have a back button to return to last visited page. your viewcontroller is put on top of the navigation stack. Think like a webpage when you navigate between pages. - presentmodalviewcontroller: you have nothing to comeback to last visited page. It is usually used for: a pop-up or to change to new branch of navigation.

The use of pushviewcontroller & presentmodalviewcontroller does not produce memory leaks.

For your application flow, I suppose that HomeActivitiesScreen is one of viewcontroller in your "bunch of tab bar". If so, create a viewcontroller that contains that tabbar and make it as root of your application (named RootViewController for example). Then:

  • When application is launched, you show the RootViewController
  • And immediately, present the modal view to your "introduction pages", then login/signup. This modal view start with a Navigation view controller structure.
  • When the user is connected, dismiss your modal view, return back to your HomeActivitiesScreen and refresh contain if need.

Like this, you do not keep the reference to your login/signup screen when you do not need.

Upvotes: 1

Mathews
Mathews

Reputation: 743

Apple handles the memory for both of these through Automatic Reference Counting. Although pushing a view controller might require more memory than presenting the same, the allocated memory is released when popping or dismissing the ViewController. ARC releases the said memory if no strong references are made from within the popped ViewController, or in other terms, the ReferenceCount is 0. So care must be taken so that no strong references are retained to the ViewContoller's objects.

Now whether to present or push a ViewController depends solely on your app design. Read this to get an outline on when to present a ViewController, .

Upvotes: 1

Amit Srivastava
Amit Srivastava

Reputation: 1105

If you use pushViewController you will automatically get a "Back" button in the navigation bar. If you use presentModalViewController you do not, and generally will have to implement your own controls and/or callbacks to handle dismissing the controller.

Conceptually the modal presentation style is generally used for atomic tasks that you cannot navigate away from (i.e. you either complete the task, or you cancel, and you cannot do anything else within the app until you do one or the other).

If you're wondering why have the difference in the first place, I can't say. Personally I think frameworks that provide a unified API for moving from one controller to another (like cocos2d, or Android) make a lot more sense.

You use modal view controllers to focus the user's attention on a Task. When you push, the user is in some kind of navigation flow, but still has the total application at their fingertips. They might decide to go forward or backward, switch to a different tab in the middle, whatever. When they get a modal view controller, they can't do any of that until the task is completed or canceled out of (the modal view is dismissed)

When you present a modal view controller, the system creates a parent-child relationship between the view controller that did the presenting and the view controller that was presented. Specifically, the view controller that did the presenting updates its modalViewController property to point to its presented (child) view controller. Similarly, the presented view controller updates its parentViewController property to point back to the view controller that presented it.

Modal view controllers provide interesting ways to manage the flow of your application. Most commonly, applications use modal view controllers as a temporary interruption in order to obtain key information from the user. However, you can also use modally presented view controllers to implement alternate interfaces for your application at specific times.

So, from my understanding this one is best option.

[self.navigationController pushViewController:view animated:YES];

Upvotes: 5

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