fast-enumeration

I found this answer: https://stackoverflow.com/a/5163334/1364174 Which presents how for in loop is implemented. NSFastEnumerationState __enumState = {0}; id __objects[MAX_STACKBUFF_SIZE]; NSUInteger __count; while ((__count = [myArray countByEnumeratingWithState:&__enumState objects:__objects count:MAX_STACKBUFF_SIZE]) > 0) { for (NSUInteger i = 0; i < __count; i++) { id obj = __objects[i]; [obj doSomething]; } } The problem is that, I found it wrong. First of all, when you have Automatic Reference Counting (ARC) turned on, you got an error Sending '__strong id *' to parameter of type '_

I'm communicating with an API that sends back an NSDictionary as a response with data my app needs (the data is basically a feed). This data is sorted by newest to oldest, with the newest items at the front of the NSDictionary. When I fast enumerate through them with for (NSString *key in articles) { ... } the order is seemingly random, and thus the order I operate on them isn't in order from newest to oldest, like I want it to be, but completely random instead. I've read up, and when using fast enumeration with NSDictionary it is not guaranteed to iterate in order through the array. However,

The goal is to compare two arrays as and check if they contain the same objects (as fast as possible - there are lots of objects in the arrays). The arrays cannot be checked with isEqual: as they are differently sorted. I already tried the solution posted here ( https://stackoverflow.com/a/1138417 - see last code snippet of the post by Peter Hosey). But this doesn't work with differently sorted arrays. The code I'm using now is the following: + (BOOL)arraysContainSameObjects:(NSArray *)array1 andOtherArray:(NSArray *)array2 { // quit if array count is different if ([array1 count] != [array2

I want to get the index of the current object when using fast enumeration, i.e. for (MyClass *entry in savedArray) { // What is the index of |entry| in |savedArray|? } Look at the API for NSArray and you will see the method - (void)enumerateObjectsUsingBlock:(void (^)(id obj, NSUInteger idx, BOOL *stop))block So give that one a try [savedArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) { //... Do your usual stuff here obj // This is the current object idx // This is the index of the current object stop // Set this to true if you want to stop }]; I suppose the most blunt

Can I expect it to go from the start of an array to the end in order? Can't find anything in the docs about this. i.e. is for (id val in array) { NSLog(@"%@", val); } always going to print out the same as for (int i = 0; i < [array count]; ++i) { NSLog(@"%@", [array objectAtIndex:i]); } Georg Fritzsche From Apples' Objective-C documentation on fast enumeration: For collections or enumerators that have a well-defined order—such as NSArray or NSEnumerator instance derived from an array—the enumeration proceeds in that order, so simply counting iterations will give you the proper index into the

I have a class and I want my class to confirm to the NSFastEnumeration Protocol. I've read the documentation but it's not really clear. Can someone please tell me what the protocol method should return and how it works? justin Apple's FastEnumerationSample shows you what to do, but here's a breakdown. The sole NSFastEnumeration method, countByEnumeratingWithState:objects:count: , returns chunks of the collection. It's executed whenever more items are needed, until it indicates that there are no more items by returning 0. A chunk is passed as a C array of id s. Within the method, the state

I have seen this over and over, why exactly is it faster to use fast enumeration in loops rather than an NSEnumerator using nextObject: . Lily Ballard NSEnumerator is the old way to enumerate over collections. It involves creating an object to represent the enumeration, then calling a method on it for every single iteration. While this was perfectly serviceable for many years, it's not terribly efficient, as it involves at least one message send for every iteration of the loop. NSFastEnumeration is the more modern approach, which leverages native language support to provide a much more

I"m wondering how to essentially transform the objective c code below into swift. This will loop through all the subviews on my desired view, check if they are textfields, and then check if they are empty of not. for (UIView *view in contentVw.subviews) { NSLog(@"%@", view); if ([view isKindOfClass:[UITextField class]]) { UITextField *textfield = (UITextField *)view; if (([textfield.text isEqualToString:""])) { //show error return; } } } Here is where i am with swift translation so far: for view in self.view.subviews as [UIView] { if view.isKindOfClass(UITextField) { //... } } Any help would