objective-c-runtime

One of the features of the modern (64 bit OS X and iPhone OS) Objective C runtime is the ability for properties to dynamically synthesize ivars without explicitly declaring them in the class: @interface MyClass : NSObject { // NSString *name; unnecessary on modern runtimes } @property (retain) NSStrng *name; @end @implementation MyClass @synthesize name; @end In quite a bit of my code I use custom getter implementations in order to initialize the properties: - (NSString *) name { if (!name) { name = @"Louis"; } return name; } The above is incompatible with synthesized ivars since it needs to

When using associated objects, an Objective-C runtime feature available starting from iOS 4 and OSX 10.6, it's necessary to define a key for storing and retrieving the object at runtime. The typical usage is defining the key like follows static char const * const ObjectTagKey = "ObjectTag"; and then use is to store the object objc_setAssociatedObject(self, ObjectTagKey, newObjectTag, OBJC_ASSOCIATION_RETAIN_NONATOMIC); and retrieve it objc_getAssociatedObject(self, ObjectTagKey); (example taken by http://oleb.net/blog/2011/05/faking-ivars-in-objc-categories-with-associative-references/ ) Is

I know declared property generates accessor method which is someway just syntax sugar. I found quite a lot people use self.property = nil in their dealloc method. 1) In Apple's Memory Management document, p23 It says: The only places you shouldn’t use accessor methods to set an instance variable are in init methods and dealloc. why shouldn't? 2) In apple's Objective-C 2.0 , p74 Declared properties fundamentally take the place of accessor method declarations; when you synthesize a property, the compiler only creates any absent accessor methods. There is no direct interaction with the dealloc

The Objective C Runtime Guide from Apple, states that you should never use objc_msgSend() in your own code, and recommends using methodForSelector: instead. However, it doesn't provide any reason for this. What are the dangers of calling objc_msgSend() in your code? Reason #1: Bad style - it's redundant and unreadable. The compiler automatically generates calls to objc_msgSend() (or some variant thereof) when it encounters Objective-C messaging expressions. If you know the class and the selector to be sent at compile-time, there's no reason to write id obj = objc_msgSend(objc_msgSend([NSObject

What is equivalent swift code for below Objective-C code. I couldn't find swift topic with runtime concept. #import <objc/runtime.h> Class class = [self class]; Trying to get class object of self ? Update: Tried with below code, got error as 'UIViewController.type' doesn't conform to protocol 'AnyObject' var klass: AnyClass = object_getClass(self) Note: Found this post, but wouldn't helped. newacct First, it's hard to translate that code to Swift without knowing what you used that class object for in Objective-C. In Objective-C, class objects are objects, and the type Class can hold a pointer

In Objective-C I can test whether a given class or instance responds to certain selectors. But how can query a class or instance for all its methods or properties of a class (e.g. a list of all methods or properties)? Ben Gottlieb You'll want to use the Objective C runtime methods, see here: https://developer.apple.com/reference/objectivec/objective_c_runtime You can do this and it is extremely well documented at https://developer.apple.com/library/mac/documentation/cocoa/Reference/ObjCRuntimeRef/index.html To fetch all the instance or class methods of a class, you may use class_copyMethodList

I have a subclass of UIScrollView in which I need to internally respond to scrolling behaviour. However, the viewcontroller will still need to listen to scrolling delegate callbacks, so I can't outright steal the delegate within my component. Is there a way to keep the property named "delegate" and just listen to messages sent along it, or else somehow internally hijack the delegate property and forward messages outward after running some code? Matt Williamson Yes, but you'll have to override every delegate method in the docs . Basically, make a second delegate property and implement the

I am trying to get a string name of a class from the class object itself. // For instance [NSArray className]; // @"NSArray" I have found object_getClassName(id obj) but that requires an instance be passed to it, and in my case that is needless work. So how can I get a string from a class object, and not an instance? NSString *name = NSStringFromClass ([NSArray class]); You can even go back the other way: Class arrayClass = NSClassFromString (name); id anInstance = [[arrayClass alloc] init]; Here's a different way to do it with slightly less typing: NSString *name = [NSArray description];