Instancetype, ID, nsobject contact and Difference

1, ID and instancetype can omit the specific type, improve the universality of the code. and NSObject * Does not have this function.

2. Instancetype can only be used for the return type of the method, and the ID use is similar to NSObject *.

3. Instancetype will tell the compiler the current type, which is similar to NSObject *, but the ID is untyped for the compiler, and calling any method will not give an error.

4, for the Init method, ID and instancetype are no different. Because the compiler will optimize the ID to instancetype. When the type that is explicitly returned is the current class, instancetype can be used to avoid the compiler error condition that the ID brings.

5, NSObject * and ID are only included with one class Isa. But NSObject contains more definitions of the methods.

6, Instancetype should be the ID and NSObject * Two deficiencies of a supplement.

Instancetype, ID, nsobject contact and Difference