viewdidappear

Guidelines for viewWillAppear, viewDidAppear, viewWillDisappear, viewDidDisappear

由 ⅰ亾dé卋堺 提交于 2019-11-28 18:21:14
Are there any guidelines for using these methods in the right manner? In particular, I would like to know what type of code I could use inside them. For example, if I have to call a method that retrieves data from a WS, where do I have to call it? Where can I register/unregister a NSNotification? etc. Manlio From UIViewController viewWillAppear: This method is called before the receiver’s view is about to be displayed onscreen and before any animations are configured for showing the view. You can override this method to perform custom tasks associated with presenting the view. For example, you

Remembering scroll position on UITableView

由 Deadly 提交于 2019-11-27 19:01:38
I have a bit of a problem with my iOS app in xcode. I have a UITableView that loads a few hundred cells. When I scroll down to a specific cell and drill down to detailedviewcontrollers and return again the master view table has returned all the way to the top. I've had a look at the following 2 questions that are similar. How can I get the UITableView scroll position so I can save it? Setting scroll position in UITableView I still can't get these to work. I'm not the most experienced coder so I'm really struggling with this. I know things like viewWillDisappear and viewDidAppear need to be

Make a custom back button for UINavigationController

由 白昼怎懂夜的黑 提交于 2019-11-27 19:01:10
问题 I'm developping an app for iOS 4.2+. I subclassed my UINavigationController to insert two UIImageView and make the navigation bar look custom. Everything is working great but I have a little problem. I created custom UIBarButtonItem and inside my view controllers i put them with : self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithCustomView:backButton]; It works too but the problem is that to make this work I need to call it from: - (void)viewDidAppear:(BOOL)animated ;

react-navigation: Detect when screen, tabbar is activated / appear / focus / blur

由 一曲冷凌霜 提交于 2019-11-27 14:24:30
问题 Perviously when I wanted to make some actions when screen is opened I put them inside componentDidMount. For example I can fetch some data. like this. componentDidMount() { this.updateData(); } But with react-navigation componentDidMount occurs only one time when user open screen first time, and if later user open this page again it will not trigger componentDidMount. What is proper way to detect when page(screen) is activated and do actions? 回答1: With react-navigation , you can do that.

Call Function in Underlying ViewController as Modal View Controller is Dismissed

由 萝らか妹 提交于 2019-11-27 13:14:35
问题 I have a mainViewController. I call [self pushModalViewController:someViewController] which makes someViewController the active view. Now I want to call a function in mainViewController as someViewController disappears with [self dismissModalViewController]. viewDidAppear does not get called probably because the view was already there, just beneath the modal view. How does one go about calling a function in the mainViewController once the modalView dismisses itself? Thanks a lot! 回答1: This

Guidelines for viewWillAppear, viewDidAppear, viewWillDisappear, viewDidDisappear

由 孤街浪徒 提交于 2019-11-27 11:15:35
问题 Are there any guidelines for using these methods in the right manner? In particular, I would like to know what type of code I could use inside them. For example, if I have to call a method that retrieves data from a WS, where do I have to call it? Where can I register/unregister a NSNotification? etc. 回答1: From UIViewController viewWillAppear: This method is called before the receiver’s view is about to be displayed onscreen and before any animations are configured for showing the view. You

Remembering scroll position on UITableView

由 [亡魂溺海] 提交于 2019-11-26 19:46:42
问题 I have a bit of a problem with my iOS app in xcode. I have a UITableView that loads a few hundred cells. When I scroll down to a specific cell and drill down to detailedviewcontrollers and return again the master view table has returned all the way to the top. I've had a look at the following 2 questions that are similar. How can I get the UITableView scroll position so I can save it? Setting scroll position in UITableView I still can't get these to work. I'm not the most experienced coder so

Unable to set frame correctly before viewDidAppear

由 ⅰ亾dé卋堺 提交于 2019-11-26 11:59:32
问题 I was wondering if anyone knows why when you set the frame of a subview in viewDidLoad and viewWillAppear the changes do not take affect on the screen, but if you set it in viewDidAppear they do? In my case I am loading a custom xib with two tableviews then attempting to shift them down in viewDidLoad to allow space for another view which is added in viewDidLoad as it is not always necessary to display it. The problem is when i set frame in viewDidLoad or viewWillAppear it is set on the
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