declared-property

I know the string name of a property of an object. How would I go about getting and setting that property using the string? While @weichsel is correct, there is a better way. Use: [anObject valueForKey: @"propertyName"]; and [anObject setValue:value forKey:@"propertyName"]; Obviously, @"propertyName" can be an NSString that is dynamically composed at runtime. This technique is called Key Value Coding and is fundamental to Cocoa. Why this is better is because -valueForKey will do what is necessary to "box" whatever type the property returns into an object. Thus, if the property is of type int ,

I know that I can't use this: myView.frame.origin.x = 25.0; and that I have to use this instead: CGRect myFrame = myView.frame; myFrame.origin.x = 25.0; myView.frame = myFrame; And I'm doing it all the time, but I don't know why I must do it that way. I would like to fill that gap in my understanding. Can someone explain ? Nowadays Xcode gives you "Expression not assignable". Some time ago you got a compile error "Lvalue required as left operand of assignment". There are two distinct dot syntaxes being used here. They look the same, but they do different things depending on what they are

I need a way to pass a property and get the name assigned to it. Any suggestions? @property (nonatomic, retain) MyObject *crazyObject; NSString *str = SOME_WAY_TO_GET_PROPERTY_NAME(crazyObject); // Above method should return @"crazyObject" You can try this: unsigned int propertyCount = 0; objc_property_t * properties = class_copyPropertyList([self class], &propertyCount); NSMutableArray * propertyNames = [NSMutableArray array]; for (unsigned int i = 0; i < propertyCount; ++i) { objc_property_t property = properties[i]; const char * name = property_getName(property); [propertyNames addObject:

What is the difference between using self.var vs. just var in an Objective-C class? Are there benefits or dangers to one or the other? foo = self.var; self.var = foo; is conceptually identical to foo = [self var]; [self setVar: foo]; So using dot notation, you are really sending messages to self. foo = var; var = foo; is conceptually the same as foo = self->var; self->var = foo; So not using dot notation to access an instance variable is the same as treating self as a pointer to a C struct and accessing the struct fields directly. In almost all cases, it is preferable to use the property

This question already has an answer here: Difference between self.var and simply var 3 answers What is the difference between self.myVariable = obj; and myVariable = obj; , when I use @propery / @synthesize to create `myVariable? It's important to note that dot-syntax is converted to a simple objc_msgSend call by the compiler: that is to say that underneath it acts exactly like a message send to the accessor for that variable. As such, all three of the following are equivalent: self.myVariable = obj; [self setMyVariable:obj]; objc_msgSend(self, @selector(setMyVariable:), obj); Of course, this