I have a table view with ten entries, which refers to another view. If I click on one cell the color changes to light grey and shows the next page. I want to set this color to black when the table view cell is clicked. How can I do this?

I have a Tab Bar Controller, which refers to two Navigation Controllers, these Navigation Controllers refer each to one view Controller. Form this View Controller you can go to another View Controller. If I switch from the first "Workflow" (e.g. thrird page) to the second and back with the Tab Bar I have to click the Button for the first Workflow twice to get to the initial view. Can I make my program to do that only by one click ? I hope you understand my problem and the structure of the program.

This is my structure of my project: >TabBarController->NavController->A1->A2->A3->A4 From the TabBarController are similar to this structure several other NavController. I want A4 to behave like there were no Nav Controller in this project. There should not be a back Button or TabBar. Like the Project were structured like this: >B1->B2 Is this possible?

I am getting the same error over and over again and I do not know why. I tried several ways to fix it, but nothing works. Building native extensions. This could take a while... ERROR:  Error installing cocoapods: ERROR: Failed to build gem native extension.     current directory: /Library/Ruby/Gems/2.6.0/gems/ffi-1.13.1/ext/ffi_c /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /Library/Ruby/Site/2.6.0 -r ./siteconf20201202-2686-t7m7nb.rb extconf.rb checking for ffi.h... * extconf.rb failed * Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers.  Check the mkmf.log file for more details.  You may need configuration options. Provided configuration options: --with-opt-dir --without-opt-dir --with-opt-include --without-opt-include=${opt-dir}/include --with-opt-lib --without-opt-lib=${opt-dir}/lib --with-make-prog --without-make-prog --srcdir=. --curdir --ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/$(RUBY_BASE_NAME) --with-ffi_c-dir --without-ffi_c-dir --with-ffi_c-include --without-ffi_c-include=${ffi_c-dir}/include --with-ffi_c-lib --without-ffi_c-lib=${ffi_c-dir}/lib --enable-system-libffi --disable-system-libffi --with-libffi-config --without-libffi-config --with-pkg-config --without-pkg-config /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:467:in `try_do': The compiler failed to generate an executable file. (RuntimeError) You have to install development tools first. from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:585:in `block in try_compile' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:534:in `with_werror' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:585:in `try_compile' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:1109:in `block in have_header' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:959:in `block in checking_for' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:361:in `block (2 levels) in postpone' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:331:in `open' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:361:in `block in postpone' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:331:in `open' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:357:in `postpone' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:958:in `checking_for' from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:1108:in `have_header' from extconf.rb:10:in `system_libffi_usable?' from extconf.rb:42:in `<main>' To see why this extension failed to compile, please check the mkmf.log which can be found here:   /Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.13.1/mkmf.log extconf failed, exit code 1 Gem files will remain installed in /Library/Ruby/Gems/2.6.0/gems/ffi-1.13.1 for inspection. Results logged to /Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.13.1/gem_make.out Something might be wrong with Ruby, but I could not figure out what I should do to fix it.

I have a four buttons and one table view in one viewController. I want to select the entries in my table with the button. E.g. I have a list of persons and one button says "family" one "friends" one "collegues" and one "unknown" by clicking on one button the table only should show the persongroup I selected. The entries of the table view are stored in an global array. Changing the array with clicking is possible (I see this in the command line), but the table does not change. Does any one know why ? For storing and selecting data I use core data. In the IBAction I do this:         guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else{             return         }         let context = appDelegate.persistentContainer.viewContext         let entityName = "Person"         let request = NSFetchRequest<NSFetchRequestResult>(entityName: entityName)         let pred = NSPredicate(format: "relationship_status CONTAINS 'friend'")         request.predicate = pred         do {             let results = try context.fetch(request)             for r in results{                 if let result = r as? NSManagedObject{                     guard let relationship_status = result.value(forKey: "relationship_status") as? String else {                         return                     }                     guard let name = result.value(forKey: "name") as? String else {                         return                     }                     self.table_entries.append(name)                     print("load")                 }             }             print ("done")             print (table_entries)         } catch  {             print(error)         }

I have an application which uses Core data. I can save and load data. But if I close xcode and reopen it all the data is gone. What step did I miss ?

I have two View Controller, lets call them A1 and A2. A1 has consits of a tableView with various entries. If I click on an entry namend "Orange" in A1, A2 should show details about Orange. To store the data I use Core Data. I filter the data I need for the Orange in A1 and now I want to pass the data like name, size etc. to A2. I tried to use a function in A1 wich sets the variables in A2. This works but when I perform the segue all the data is gone. What can I do to pass the data? func initializer(caption: String, size : String, text: String) {         self.text = text         self.fruitCaption = caption         self.fruitSize = size     } I call this initializer function from A1, the function itself is placed in A2.

I have a normal label and want that Label to blink three times, by changing the backgroundcolor from red to black an so on. I did some research and many people work with Timer or animations, but I cannot change this methods, like I need them. What can I do to make my Label blink?

Yesterday Xcode worked fine, after some time (I surfed on the internet) xcode had a problem and restarted itself. After reopening it, Xcode had a problem while building the app. So I restart my Mac, after that the app worked fine on the simulator, but all the data I stored in core data was gone. I there a way to rebuild the data?

Xcode crashed unexpectedly last week. After restarting, Xcode had a problem so I restarted my MacBook. I reopened Xcode and started a simulation and no Data where shown, so I debugged through my code and the Context file seems to be empty. Now I have several questions: 1) Has anybody an idea why this happened ? 2) How can I prevent this problem? 3) Are context files for persistent data savings anyway?

I have a long String which I want to shorten step by step. The String contains a lot of characters which I don't need, but the String has some patterns, so I search for a character, shorten the original String or rather the copy of the original String and search for the next relevant character. let searchname = ""         let f = globalString.firstIndex(of: "\"")         self.globalString.dropFirst(f)         let e = globalString.firstIndex(of: "\\")         let substring = globalString[...e!]         return String(substring) In line three I get the error, that an Integer is needed and a String.index is given. How can I transform the String.index to an Integer or is there another possibility to this in code?

I am using an AVSpeechSythesizer(), which reads the list (TableViewCells) on one view to the user, if the user hits a button. If the user hits the button again the AVSpeechSynthesizer() stops, as I want it to be. But I want the AVSpeechSynthesizer() to stop as well, if the user change the view (go back or hit the home Button). Is it possible that the ViewController of that view get Notification, if the View is no longer shown or have I to check in the other ViewControllers?

I used the storyboard and horizontal and vertical stack views to generate a good looking App. This worked fine, but one view does not show the Table View I placed there. In the storyboard everything is fine and no warning is shown. I tried to remove the Table View and renew it, but that did not fix the problem. Has anybody an idea what I missed ?

To make my App look better, I'd like to add some color gradient in the background of my labels and Table View Cells. If I add a Sublayer the text in the Label is not visible anymore. Is there a possibility to add the sublayer as a background color or behind the textLabel ? Or should I convert the textLabel into a sublayer of the table view cell ? And if so how?

I have two json files and want to insert them into core data. Therefor I'd like to convert the json into a dictionary (maybe it is as simple as in python?) and insert the key value pairs one by one into core Data. The json is build as followed: {1 : { "title" : "Mini pork pies with piccalilli", "category" : "meat"}, 2 : {"title" : "apple crumble", "category" : "dessert"}} I only was able to get the json file and hopefully converted it into a dictionary (as you can see in the code below). Now I do not know what to do next. let asset = NSDataAsset(name: "Captions")         let data = (asset?.data)!         do{             let json = try JSONSerialization.jsonObject(with: data, options: [])             if let object = json as? [Int : Any] {                 print(object)                 return json as! DictionaryInt, AnyObject             }else if let object = json as? [Any] {                 for anItem in object as! [DictionaryInt, AnyObject]{                    print("Not an dictionary, think of something else")                 }             }