__NSArrayI is a code-word for an immutable array – that is, a “regular” NSArray which you cannot change. __NSArrayM is a code-word for a mutable array – that is, NSMutableArray. In NSMutableArray, you can add and remove items.
NSPredicate *predicate = [NSPredicate predicateWithFormat:@”type == %@”, @”standard”]; NSArray *filteredArray = [myArray filteredArrayUsingPredicate:predicate]; id firstFoundObject = nil; firstFoundObject = filteredArray.count > 0 ? filteredArray.firstObject : nil; NB: The notion of the first found object in an NSSet makes no sense since the order of the objects in a set is undefined.
I found this bit of code awhile ago (can’t remember who to attribute it to). It’s quite ingenius, using a Category to allow the creation of a mutable array that does no retain/release by backing it with a CFArray with proper callbacks. @implementation NSMutableArray (WeakReferences) + (id)mutableArrayUsingWeakReferences { return [self mutableArrayUsingWeakReferencesWithCapacity:0]; } + (id)mutableArrayUsingWeakReferencesWithCapacity:(NSUInteger)capacity { … Read more
The stroke/fill colors only affect the -stroke command. They don’t affect the -appendPath: command. Paths don’t contain per-segment color information. If you need a multi-colored line you’re going to need to stroke each color separately.
They are almost identical, but not completely. The Clang documentation on Objective-C Literals states: Array literal expressions expand to calls to +[NSArray arrayWithObjects:count:], which validates that all objects are non-nil. The variadic form, +[NSArray arrayWithObjects:] uses nil as an argument list terminator, which can lead to malformed array objects. So NSArray *myArray = @[objectOne, objectTwo, … Read more
NSArray *contacts = …; //your array of NSDictionary objects NSPredicate *filter = [NSPredicate predicateWithFormat:@”contact_type = 42″]; NSArray *filteredContacts = [contacts filteredArrayUsingPredicate:filter]; After this, filteredContacts will contain only the contacts whose contact_type is 42. If you need to search for more than one kind of contact_type, then simply use an OR in the predicate: filter = … Read more
It can be done in a single line if you like key-value coding (KVC). The @unionOfArrays collection operator does exactly what you are looking for. You may have encountered KVC before in predicates, bindings and similar places, but it can also be called in normal Objective-C code like this: NSArray *flatArray = [array valueForKeyPath: @”@unionOfArrays.self”]; … Read more
Use NSSortDescriptor. Just search the documentation on it and there some very simple examples you can copy right over. Here is a simplified example: NSSortDescriptor *valueDescriptor = [[NSSortDescriptor alloc] initWithKey:@”MyStringVariableName” ascending:YES]; NSArray *descriptors = [NSArray arrayWithObject:valueDescriptor]; NSArray *sortedArray = [myArray sortedArrayUsingDescriptors:descriptors]; And just like that you have a sorted array.
Try this magic: NSDictionary *dict = [NSDictionary dictionaryWithObjects:records forKeys:[records valueForKey:@”intField”]]; FYI this is possible because of this built-in feature: @interface NSArray(NSKeyValueCoding) /* Return an array containing the results of invoking -valueForKey: on each of the receiver’s elements. The returned array will contain NSNull elements for each instance of -valueForKey: returning nil. */ – (id)valueForKey:(NSString *)key;
Expanding on Paul Lynch’s answer, here’s an example I have doing exactly this using a comparison method as a category on NSString. This code handles only the case of numbers followed by optional non-numeric qualifiers, but you could extend it to handle cases like “1a10” etc. if desired. Once you create the category method, you … Read more