Any definition that contains the [Protocol] attribute will actually generate three supporting classes that vastly improve the way that you consume protocols:. The class implementation provides a complete abstract class that you can override individual methods of and get full type safety. But due to C not supporting multiple inheritance, there are scenarios where you might needs to have a different base class, but you still want to implement an interface, that is where the.
The generated interface definition comes in. It is an interface that has all the required methods from the protocol. This allows developers that want to implement your protocol to merely implement the interface. The runtime will automatically register the type as adopting the protocol.
Notice that the interface only lists the required methods and does expose the optional methods. This means that classes that adopt the protocol will get full type checking for the required methods, but will have to resort to weak typing manually using [Export] attributes and matching the signature for the optional protocol methods.
To make it convenient to consume an API that uses protocols, the binding tool also will produce an extensions method class that exposes all of the optional methods. This means that as long as you are consuming an API, you will be able to treat protocols as having all the methods.
If you want to use the protocol definitions in your API, you will need to write skeleton empty interfaces in your API definition. The above is needed because at binding time the IMyProtocol would not exist, that is why you need to provide an empty interface. The implementation for the required interface methods gets exported with the proper name, so it is equivalent to this:. This will work for all required protocol members, but there is a special case with optional selectors to be aware of.
Optional protocol members are treated identically when using the base class:. The IDE will add it via autocomplete when you add it starting with override. Some rare classes can behave differently here. In almost all cases however it is safe to use either. In Objective-C it is possible to extend classes with new methods, similar in spirit to C 's extension methods.
When one of these methods is present, you can use the [BaseType] attribute to flag the method as being the receiver of the Objective-C message. For example, in Xamarin. This declares the method as internal, hiding the above API from users, but exposing it to the library. Then you can write a method like this:. Usually these fields contain strings or integers values that must be referenced. They are commonly used as string that represent a specific notification and as keys in dictionaries.
To bind a field, add a property to your interface definition file, and decorate the property with the [Field] attribute. This attribute takes one parameter: the C name of the symbol to lookup. For example:. If you want to wrap various fields in a static class that does not derive from NSObject , you can use the [Static] attribute on the class, like this:.
The [Field] attribute can be applied to the following data types:. In addition to the native field name, you can specify the library name where the field is located, by passing the library name:. You can add enum directly in your binding files to makes it easier to use them inside API definitions - without using a different source file that needs to be compiled in both the bindings and the final project.
It is also possible to create your own enums to replace NSString constants. In this case the generator will automatically create the methods to convert enums values and NSString constants for you. In the above example you could decide to decorate void Perform NSString mode ; with an [Internal] attribute.
This will hide the constant-based API from your binding consumers. However this would limit subclassing the type as the nicer API alternative uses a [Wrap] attribute. Those generated methods are not virtual , i. An alternative is to mark the original, NSString -based, definition as [Protected]. This will allow subclassing to work, when required, and the wrap'ed version will still work and call the overriden method.
The attribute can be used to create better, more accurate,. You can decorate methods on return value , parameters and properties with [BindAs]. The only restriction is that your member must not be inside a [Protocol] or [Model] interface. Internally we will do the bool?
Please see the [BindAs] documentation to see supported conversion types. Notifications are messages that are posted to the NSNotificationCenter. DefaultCenter and are used as a mechanism to broadcast messages from one part of the application to another. When an application posts a message to the notification center, it typically contains a payload stored in the NSNotification.
UserInfo dictionary. This dictionary is weakly typed, and getting information out of it is error prone, as users typically need to read in the documentation which keys are available on the dictionary and the types of the values that can be stored in the dictionary.
The presence of keys sometimes is used as a boolean as well. The Xamarin. To do this, you set the [Notification] attribute on a property that has been also been tagged with a [Field] property it can be public or private. This attribute can be used without arguments for notifications that carry no payload, or you can specify a System. Type that references another interface in the API definition, typically with the name ending with "EventArgs". The generator will turn the interface into a class that subclasses EventArgs and will include all of the properties listed there.
The [Export] attribute should be used in the EventArgs class to list the name of the key used to look up the Objective-C dictionary to fetch the value. The above code will generate a nested class MyClass. Notifications with the following methods:. Users of your code can then easily subscribe to notifications posted to the NSDefaultCenter by using code like this:. The returned value from ObserveDidStart can be used to easily stop receiving notifications, like this:. Or you can call NSNotification.
RemoveObserver and pass the token. If your notification contains parameters, you should specify a helper EventArgs interface, like this:. The [ProbePresence] attribute is used for the generator to probe if the key is set in the UserInfo , instead of trying to extract the value. This is used for cases where the presence of the key is the value typically for boolean values. Categories are an Objective-C mechanism used to extend the set of methods and properties available in a class.
In practice, they are used to either extend the functionality of a base class for example NSObject when a specific framework is linked in for example UIKit , making their methods available, but only if the new framework is linked in. In some other cases, they are used to organize features in a class by functionality. They are similar in spirit to C extension methods. This is what a category would look like in Objective-C:. The above example if found on a library would extend instances of UIView with the method makeBackgroundRed.
To bind those, you can use the [Category] attribute on an interface definition. When using the [Category] attribute, the meaning of the [BaseType] attribute changes from being used to specify the base class to extend, to be the type to extend. The following shows how the UIView extensions are bound and turned into C extension methods:. In some other cases, categories are used not to extend a system class, but to organize functionality, purely for decoration purposes.
Like this:. Although you can use the [Category] attribute also for this decoration style of declarations, you might as well just add them all to the class definition. Both of these would achieve the same:.
Blocks are a new construct introduced by Apple to bring the functional equivalent of C anonymous methods to Objective-C. For example, the NSSet class now exposes this method:. The above description declares a method called enumerateObjectsUsingBlock: that takes one argument named block. This block is similar to a C anonymous method in that it has support for capturing the current environment the "this" pointer, access to local variables and parameters.
To bind this kind of API with btouch, you need to first declare the block type signature as a C delegate and then reference it from an API entry point, like this:. You can use the [Async] attribute on methods that return void and whose last argument is a callback. When you apply this to a method, the binding generator will generate a version of that method with the suffix Async.
Perhaps you can open a new question with details of the data format you're trying to read and write, and we can help you build a portable system to do that. That said, taking language-specific object serialization from one language to another is always going to be challenging at best. BTW, if what you need is tight, low-level integration with existing C , you should look at the mono project.
Show 2 more comments. Obj-C supports templates since Xcode v7. Community Bot 1 1 1 silver badge. Anton Anton 4 4 silver badges 7 7 bronze badges. Note: this supports compile time checking and not runtime enforcement.
Add a comment. JulianSymes JulianSymes 2, 21 21 silver badges 24 24 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown.
The Overflow Blog. Podcast Making Agile work for data science. Stack Gives Back Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Visit chat. Asked 9 years, 9 months ago. Active 4 years, 10 months ago. Viewed 19k times. Everything is in the title : Is there any templates in ObjC? Any helps will be strongly thanks :. CharlesB This isn't possible.
Ross III. Just rename your. Show 1 more comment. Active Oldest Votes. Rob Napier Rob Napier k 34 34 gold badges silver badges bronze badges. In Fact, I need to send information in byte[] to a server, in c. I must respect the same class organization, with their names, inheritance, and template. Writing a network protocol has no relationship at all to the class implementations.
I don't choose it : It's because I must follow this implementation because I have to send, into byte[], thoses classes to be understandable by server — UIChris. Bytes are bytes. They're not related to the implementation that writes them. I can write the same bytes in Perl as I can write in C. I can write data that says "This piece of data represents a template instantiation on 'x'" in any language without requiring that the language itself support templates.
Perhaps you can open a new question with details of the data format you're trying to read and write, and we can help you build a portable system to do that.
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