Look to the parent class (NSDictionary) – (NSArray *)allKeysForObject:(id)anObject Which will return a NSArray of all the keys for a given Object Value. BUT it does this by sending an isEqual message to each object of the Dictionary so for your large dataset this may not be best performance. Maybe you need to hold some … Read more
If every element in the array is a dictionary containing a certain key, you can sort the array using a sort descriptor. For instance, if every element is a dictionary containing a key called “name”: NSSortDescriptor *sortByName = [NSSortDescriptor sortDescriptorWithKey:@”name” ascending:YES]; NSArray *sortDescriptors = [NSArray arrayWithObject:sortByName]; NSArray *sortedArray = [array sortedArrayUsingDescriptors:sortDescriptors];
use: let jsonDic = NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers, error: &error) as Dictionary<String, AnyObject>;
NSMutableDictionary isn’t designed to be thread-safe data structure, and simply marking the property as atomic, doesn’t ensure that the underlying data operations are actually performed atomically (in a safe manner). To ensure that each operation is done in a safe manner, you would need to guard each operation on the dictionary with a lock: // … Read more
As NSDictionarys are only designed to deal with objects, a simple way to do this is to wrap the integer and float in a NSNumber object. For example: NSMutableDictionary *testDictionary = [[NSMutableDictionary alloc] init]; [testDictionary setObject:[NSNumber numberWithFloat:1.23f] forKey:[NSNumber numberWithInt:1]]; NSLog(@”Test dictionary: %@”, testDictionary); [testDictionary release]; To extract the relevant value, simply use the appropriate intValue, … Read more
Use -mutableCopy. NSDictionary *d; NSMutableDictionary *m = [d mutableCopy]; Note that -mutableCopy returns id (Any in Swift) so you will want to assign / cast to the right type. It creates a shallow copy of the original dictionary.
There isn’t a built in way, but I just usually use mutableCopy like this: NSMutableArray *array = [@[ @”1″, @”2″, @”3″ ] mutableCopy];
The NSDictionary and NSMutableDictionary docs are probably your best bet. They even have some great examples on how to do various things, like… …create an NSDictionary NSArray *keys = [NSArray arrayWithObjects:@”key1″, @”key2″, nil]; NSArray *objects = [NSArray arrayWithObjects:@”value1″, @”value2″, nil]; NSDictionary *dictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys]; …iterate over it for (id key in dictionary) { … Read more
A standard way would look like this for(id key in myDict) { id value = [myDict objectForKey:key]; [value doStuff]; }
setValue:forKey: is part of the NSKeyValueCoding protocol, which among other things, lets you access object properties from the likes of Interface Builder. setValue:forKey: is implemented in classes other than NSDictionary. setObject:forKey: is NSMutableDictionary’s reason to exist. Its signature happens to be quite similar to setValue:forKey:, but is more generic (e.g. any key type). It’s somewhat … Read more