nsobject

I'm working in Objective-C on the iPhone and need to know whether a 'Class' inherits from 'NSObject'. I tried checking if it responds to an NSObject selector: bool success = [myClass respondsToSelector:@selector(class)]; but you can guess what happened... it didn't even respond to "respondsToSelector:" so it throws a "does not implement doesNotRecognizeSelector:" exception. I tried to catch that exception, but it looks like it can't be caught with a @try-@catch. Any ideas? Go direct to the Objective-C runtime: #import <objc/runtime.h> /* originally posted version — works because eventually

I stumbled upon this post In Objective-C why should I check if self = [super init] is not nil? I can understand this syntax : - (id)initWithString:(NSString *)aString { self = [super init]; if (self) { instanceString = [aString retain]; } return self; } or this syntax : - (id)init; { if (!(self = [super init])) return nil; // other stuff return self; } but I still don't understand the "standard" template syntax - init { if((self = [super init])) { // set up instance variables and whatever else here } return self; } Can someone tell as clearly as possible what (3) does more or less compared to

This question was inspired by mz2's answer on the question Check for object type fails with "is not a type" error . Consider an empty Swift class: class MyClass { } Attempting to call any NSObjectProtocol methods on an instance of this class will result in a compile-time error: let obj = MyClass() obj.isKindOfClass(MyClass.self) // Error: Value of type 'MyClass' has no member 'isKindOfClass' However, if I cast the instance as AnyObject , my object now conforms to NSObjectProtocol and I can call the instance methods defined by the protocol: let obj: AnyObject = MyClass() obj.isKindOfClass

That's it. Why would anyone want (at least as a public API) a method such as that? Is there any practical use for it? The self method is useful for Key-Value Coding (KVC). With KVC, you can treat an object somewhat like a dictionary. You can access a property of the object using a string containing the name of the property, like this: [view valueForKey:@"superview"] . You walk down a chain of properties using a string containing a key path, like this: [view valueForKeyPath:@"superview.superview.center"] . Since NSObject has a self method, you can use self as the key or key path: [view

This is an already answer question within SO but I cannot find it in the Apple documentation anywhere . Could you point me in the right direction? Within the following topics Do I have to retain an object before passing it to -performSelector:withObject:afterDelay:? the effect on retain count of performSelector:withObject:afterDelay:inModes Is object that calls performSelector:withObject:afterDelay get retained by the NSRunLoop? the default behaviour seems to be the following: it retains the receiver and the argument(s) . I'm using the following code [[self delegate] performSelector:@selector