When you want to return a value from a method, you put the type you want to return in the first set of parentheses.
- (NSString)returnHello {
return @"Hello World";
}
The value you want to return goes after the return keyword;
A class method is called on the class the method belongs to, not an instance of it. This is possible because Objective-C classes are also objects. To denote a method as a class method, change the - to a +:
+ (void)hello {
NSLog(@"Hello World");
}
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 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
...
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...
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...
It is also possible to write a context manager using generator syntax thanks to the contextlib.contextmanager decorator:
import contextlib
@contextlib.contextmanager
def context_manager(num):
print('Enter')
yield num + 1
print('Exit')
with context_manager(2) as cm:
# the ...
Intents can be used to broadcast messages to other components of your application (such as a running background service) or to the entire Android system.
To send a broadcast within your application, use the LocalBroadcastManager class:
Intent intent = new Intent("com.example.YOUR_ACTION"...
