What is a Singleton Class?
A singleton class returns the same instance no matter how many times an application requests it. Unlike a regular class, A singleton object provides a global point of access to the resources of its class.
When to Use Singleton Classes?
Singletons are used in situations ...
Objective-C supports a special type called `instancetype that can only be used as type returned by a method. It evaluates to the class of the receiving object.
Consider the following class hierarchy:
@interface Foo : NSObject
- (instancetype)initWithString:(NSString *)string;
@end
@interf...
You can enhance your own classes with generics just like NSArray or NSDictionary.
@interface MyClass<__covariant T>
@property (nonnull, nonatomic, strong, readonly) NSArray<T>* allObjects;
- (void) addObject:(nonnull T)obj;
@end
In most object oriented languages, allocating memory for an object and initializing it is an atomic operation:
// Both allocates memory and calls the constructor
MyClass object = new MyClass();
In Objective-C, these are separate operations. The class methods alloc (and its historic sibling allo...
