Calling an instance method:
[classInstance hello];
@interface Sample
-(void)hello; // exposing the class Instance method
@end
@implementation Sample
-(void)hello{
NSLog(@"hello");
}
@end
Calling an instance method on the current instance:
[self hell...
Abstract classes are classes that are meant to be inherited but avoid implementing specific methods, leaving behind only method signatures that subclasses must implement.
Abstract classes are useful for defining and enforcing class abstractions at a high level, similar to the concept of interfaces ...
A Broadcast receiver is an Android component which allows you to register for system or application events.
A receiver can be registered via the AndroidManifest.xml file or dynamically via the Context.registerReceiver() method.
public class MyReceiver extends BroadcastReceiver {
@Override
...
The where method is available on any ActiveRecord model and allows querying the database for a set of records matching the given criteria.
The where method accepts a hash where the keys correspond to the column names on the table that the model represents.
As a simple example, we will use the foll...
The where method on any ActiveRecord model can be used to generate SQL of the form WHERE column_name IN (a, b, c, ...). This is achieved by passing an array as argument.
As a simple example, we will use the following model:
class Person < ActiveRecord::Base
#attribute :first_name, :string
...
Scopes act as predefined filters on ActiveRecord models.
A scope is defined using the scope class method.
As a simple example, we will use the following model:
class Person < ActiveRecord::Base
#attribute :first_name, :string
#attribute :last_name, :string
#attribute :age, :integer
...
Defining Strings in the strings.xml file also allows for string formatting. The only caveat is that the String will need to be dealt with in code like below, versus simply attaching it to a layout.
<string name="welcome_trainer">Hello Pokémon Trainer, %1$s! You have caught %2$d Poké...
Unlike C++ in C# you can call a virtual method from class constructor (OK, you can also in C++ but behavior at first is surprising). For example:
abstract class Base
{
protected Base()
{
_obj = CreateAnother();
}
protected virtual AnotherBase CreateAnother()
{
...
You can create a CALayer and set its frame like this:
Swift:
let layer = CALayer()
layer.frame = CGRect(x: 0, y: 0, width: 60, height: 80)
Objective-C:
CALayer *layer = [[CALayer alloc] init];
layer.frame = CGRectMake(0, 0, 60, 80);
You can then add it as a sublayer to an existing CALayer...
To add a method to a button, first create an action method:
Objective-C
-(void)someButtonAction:(id)sender {
// sender is the object that was tapped, in this case its the button.
NSLog(@"Button is tapped");
}
Swift
func someButtonAction() {
print("Button is tapped...
You can easily transform every component in a clickable button using the MouseArea component. The code below displays a 360x360 window with a button and a text in the center; pressing the button will change the text:
import QtQuick 2.0
Rectangle {
width: 360
height: 360
Rectang...
To find all the files of a certain extension within the current path you can use the following find syntax. It works by making use of bash's built-in glob construct to match all the names having the .extension.
find /directory/to/search -maxdepth 1 -type f -name "*.extension"
To find ...
Since Git 1.7.12 it is possible to rebase down to the root commit. The root commit is the first commit ever made in a repository, and normally cannot be edited. Use the following command:
git rebase -i --root
Note that you cannot overload a function based on its return type. For example:
// WRONG CODE
std::string getValue()
{
return "hello";
}
int getValue()
{
return 0;
}
int x = getValue();
This will cause a compilation error as the compiler will not be able to work out wh...
Filters can either be defined in a method and then added to Jinja's filters dictionary, or defined in a method decorated with Flask.template_filter.
Defining and registering later:
def format_datetime(value, format="%d %b %Y %I:%M %p"):
"""Format a date time to (Defau...
