I programmatically create several tables and the code has worked fine for years. It did not generate any warnings two weeks ago when I last ran it. I\u2019ve since updated to Xcode 8.3 and 10.10.3 and now get three warnings for each UITableViewController.<\/p>\n
\nMethod override for the designated initializer of the superclass '-initWithStyle:' not found.\nMethod override for the designated initializer of the superclass '-initWithCoder:' not found.\nMethod override for the designated initializer of the superclass '-initWithNibName:bundle:' not found.\n<\/code><\/pre>
\nThe code to initialize the table is similar for all of my tables:<\/p>\n\n- (instancetype)initInManagedObjectContext:(NSManagedObjectContext *)context \n withScoreKeeper:(ScoreKeeper *)scorer \n withWordList:(WordList *)wordlist {\n\n self = [super initWithStyle:UITableViewStyleGrouped];\n\n if (self) {\n _mObjContext = context;\n _scoreKeeper = scorer;\n _wordList = wordlist;\n }\n return self;\n}\n<\/code><\/pre>
\nand the .h looks like this:<\/p>\n\n@interface SettingsTableViewController : UITableViewController {\n UIPopoverController *popover;\n\n}\n - (instancetype)initInManagedObjectContext:(NSManagedObjectContext *)context \n withScoreKeeper:(ScoreKeeper *)scorer \n withWordList:(WordList *)wordlist NS_DESIGNATED_INITIALIZER;\n<\/code><\/pre><\/p>\nHere\u2019s what I found out. I am not a programmer, so parts could be mistaken.<\/p>\n
When I opened my project for the first time with Xcode 5 and Xcode 6, I was prompted to “Convert to Modern Objective-C Syntax”. (The latest version of Xcode puts it under Edit > Convert > Convert to Modern Objective-C Syntax.) I allowed Xcode to convert everything and understood most of the changes. I understood how NS_DESIGNATED_INITIALIZER works but not why it works. Since I had no compiler errors and everything worked as before, I promptly forgot about it. In the latest version of Xcode, they appear to have updated the compiler and that\u2019s what triggered my warning message.<\/p>\n
From Apple\u2019s notes: Adopting Modern Objective C<\/a><\/p>\n\nUsing this macro introduces a few restrictions:<\/p>\nThe implementation of a designated initializer must chain to a superclass init method (with [super init…]) that is a designated initializer for the superclass.<\/p>\n
The implementation of a convenience initializer (an initializer not marked as a designated initializer within a class that has at least one initializer marked as a designated initializer) must delegate to another initializer (with [self init…]).<\/p>\n
If a class provides one or more designated initializers, it must implement all of the designated initializers of its superclass.\n<\/p><\/div>\n
Here\u2019s what I think happened. First, I got three warning messages because UITableViewController has three designated initializers.
\n
\n- (instancetype)initWithStyle:(UITableViewStyle)style NS_DESIGNATED_INITIALIZER;\n- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil NS_DESIGNATED_INITIALIZER;\n- (instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;\n<\/code><\/pre>
\nI violated the third restriction because I did not implement all of the designated initializers of the superclass.<\/p>\nRemoving the NS_DESIGNATED_INITIALIZER macro from the .h files made the warnings go away. <\/p>\n
The question then arises, Do I care that these classes have no designated initializers? Probably not.
\nFirst, there are no other initializers in these classes, so I won\u2019t accidentally call the wrong one. Second, I\u2019m not a programmer by training, so when I started writing apps, I used the procedural programming style that I was used to. Until recently, I had never subclassed a class. So I won\u2019t be subclassing this one and there won\u2019t be any subclasses to worry about. Now that I know a bit more about Objective C, it turns out that every class I wrote was a subclass of one of iOS\u2019s classes and that actually explains a bit about why I was getting the errors.<\/p>\n
I did not realize that I could create the table view object by calling a method on its superclass. For example, this call works:
\n
\nSettingsTableViewController *stvc = [[SettingsTableViewController alloc] initWithStyle: UITableViewStyleGrouped];\n<\/code><\/pre>
\nIt works even when I have NS_DESIGNATED_INITIALIZER set. Presumably no other warnings are sent because the compiler is already complaining about not calling a designated initializer of super.<\/p>\nAnd as long as the views called in the table view do not need any of the objects that were passed in, everything is fine. If a view that is linked to in the table does need one of the objects, then obviously the app crashes. <\/p>\n
Since I never want to call anything but the designated initializer, it was suggested that I use NSAssert() to make sure that I don\u2019t call the designated initializers of my superclass, and make all the warnings go away with this code:
\n
\n- (instancetype)initWithStyle:(UITableViewStyle)style {\n NSAssert(NO, @"%@", @"Tried to implement with initWithStyle");\n self = [self initInManagedObjectContext:nil withScoreKeeper:nil withWordList:nil];\n return self;\n}\n\n- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {\n NSAssert(NO, @"%@", @"Tried to implement with initWithNibName");\n self = [self initInManagedObjectContext:nil withScoreKeeper:nil withWordList:nil];\n return self;\n}\n- (instancetype)initWithCoder:(NSCoder *)aDecoder {\n NSAssert(NO, @"%@", @"Tried to implement with initWithCoder");\n self = [self initInManagedObjectContext:nil withScoreKeeper:nil withWordList:nil];\n return self;\n}\n<\/code><\/pre>
\nNow I get this error in the log when I try to call initWithStyle directly.
\n\n*** Assertion failure in -[SettingsTableViewController initWithStyle:], \/Users\/jscarry\/Words\/Words\/Settings\/SettingsTableViewController.m:37\n<\/code><\/pre><\/p>\nThis<\/a> stackoverflow question has some useful info.<\/p>\n This articleUpdate: I found this article (UITableViewController Designated Initializer Woes<\/a>) where they have a more complete explanation of the issue and a more complete fix.<\/p>\n","protected":false},"excerpt":{"rendered":"I programmatically create several tables and the code has worked fine for years. It did not generate any warnings two weeks ago when I last ran it. I\u2019ve since updated to Xcode 8.3 and 10.10.3 and now get three warnings for each UITableViewController. Method override for the designated initializer of the superclass '-initWithStyle:' not found. … Continue reading NS_DESIGNATED_INITIALIZER warnings<\/span><\/a><\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[21],"tags":[],"class_list":["post-2222","post","type-post","status-publish","format-standard","hentry","category-ios"],"_links":{"self":[{"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=\/wp\/v2\/posts\/2222","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2222"}],"version-history":[{"count":0,"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=\/wp\/v2\/posts\/2222\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2222"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2222"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wellgolly.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2222"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}