subclass

This is utterly baffling to me, making me think I've missed something essential. But I'm trying to create a view controller container to manage two panes (similar to a SplitViewController but with some crucial differences). I've barely begun constructing the class, so I've only got 3 iVars right now: @implementation SplitViewController{ BOOL _showLeftPane; UIViewController *_leftController; UIViewController *_rightController; } No matter what I do, I cannot assign a view controller to the _leftController iVar. Mostly, the _rightController iVar can assign. It get's weirder. If I switch the

I know that I can "subclass" an NSMutableArray using "category extensions," i.e. @interface NSMutableArray (MyExtension) , to add new functions to the class. However, is there a way using category extensions to also add new properties to the extension? Note that @interface NSMutableArray (MyStuff) is a category and not a class extension . They are similar in this context, but actually do have quite a few different details. You can't add storage to an existing class through either mechanism. You can use Associative References to associate data with an instance, though. As you said, categories

I would like to subclass TToolBar with another class called MyTToolBar so that I can override a method. I'm new to Delphi, but after two hours of trying various methods, I can't get MyTToolBar to be used instead of TToolBar. I can't be the first person who's wanted to override a method on a visual component class. I come more from an Xcode background where subclassing a visual component is easy. You create a subclass (e.g., MySubclass) of a parent class (e.g., MySuperClass) and then just simply assign the subclass in the Interface Builder view of Xcode. The subclass is automatically recognized

I've been trying this, but I can't seem to figure this out. I want to do this... public abstract class SingletonType<TSingleton, TBaseClass> : TBaseClass where TSingleton : TBaseClass, new() where TBaseClass : class { static TSingleton _singleton; public static TSingleton Singleton => _singleton ?? (_singleton = new TSingleton()); } The plan was to use it like this which would sort of 'wrap' the singleton pattern around a base class... public class SingletonFoo : SingletonType<SingletonFoo, Foo> { } However, I keep getting this Cannot derive from 'TBaseClass' because it is a type parameter Um.

I have heard that when you have a subclass, you are supposed to initialize the superclass with the same init function from within the subclass's init. What I mean is that the subclass's init should call [super init] and the subclass's initWithFrame should call [super initWithFrame]. Why is this? Why does calling the super's init from a subclass's initWithFrame result in an infinite loop? If this is required, then does this mean I can't create a new init function within a subclass such as initWithPoint and have that call super's init or initWithFrame simply because the super class doesn't have

I am using a VideoView and the MediaController for an app I am working on. I simply wanted to have the MediaController appear on top of my VideoView but apparently you can't do that very easily. I attempted to use the setAnchorView method to my VideoView id, but that didn't work. No matter what I do, the MediaController is always at the bottom of my screen. With that said, I did some research and it looks as if I go about extending MediaController , I can change position and other properties. I have created a new class: package com.dop.mobilevforum; import android.content.Context; import

I would like to subclass numpy ndarray. However, I cannot change the array. Why self = ... does not change the array? Thanks. import numpy as np class Data(np.ndarray): def __new__(cls, inputarr): obj = np.asarray(inputarr).view(cls) return obj def remove_some(self, t): test_cols, test_vals = zip(*t) test_cols = self[list(test_cols)] test_vals = np.array(test_vals, test_cols.dtype) self = self[test_cols != test_vals] # Is this part correct? print len(self) # correct result z = np.array([(1,2,3), (4,5,6), (7,8,9)], dtype=[('a', int), ('b', int), ('c', int)]) d = Data(z) d.remove_some([('a',4)])

I'm trying to implement the answer to this SO question . The problem is: -[drawTextInRect] is apparently not called, and setting the shadow in -[drawRect] doesn't make the UITextField's text shadowed. Another weird thing is that even if my subclass implementations of -[drawTextInRect] and -[drawRect] are completely empty (not even a call to super), the textfield's text is drawn. This is a bug in the UITextField API documentation. The documentation indicates that overriding drawTextInRect: can be used to customize behaviour. This is not the case. In fact, drawTextInRect: will never be called on