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There is a class named AdventurePiece, I create a pointer to that class named failPiece, then I allocate memory for it and initializes it´s variables.
But these firstChoice, secondChoice & so on.. what are they? I know they are member classses declared and implemented in AdventurePiece (*.h and *.m) But what is this I am doing here exactly called? I create a pointer to object named failPiece and then I set the values of these member classes - what is this I am doing here called?
AdventurePiece *failPiece = [[AdventurePiece alloc] initWithMessage: @\"Cutting the blue wire begins a chain reaction - omg that is bad. Like really bad..Kaboom! What went wrong!?!\" firstChoice:@\"Too Bad\" secondChoice:nil firstPiece:nil secondPiece:nil isEnd:YES];
There is a class named AdventurePiece, I create a pointer to that class named failPiece, then I allocate memory for it and initializes it´s variables.
But these firstChoice, secondChoice & so on.. what are they? I know they are member classses declared and implemented in AdventurePiece (*.h and *.m) But what is this I am doing here exactly called? I create a pointer to object named failPiece and then I set the values of these member classes - what is this I am doing here called?
AdventurePiece *failPiece = [[AdventurePiece alloc] initWithMessage: @\"Cutting the blue wire begins a chain reaction - omg that is bad. Like really bad..Kaboom! What went wrong!?!\" firstChoice:@\"Too Bad\" secondChoice:nil firstPiece:nil secondPiece:nil isEnd:YES];
You need to read up on basic Objective C. fistPiece, secondPiece, etc, are not "member classes." That term is not used in Objective C. It would be a bit like calling something a "foul strike" in baseball.
Creating an objective C object is a 2 step process. You use alloc to create the storage for an object. You then send an init message to the newly allocated object to get it to set itself up for use. You must send an init method to every object before you can use it.
Init methods come in different flavors. Some init methods don't take any parameters. Some take one or more.
When you call an init method with multiple parameters, you are providing extra information that is used by the init method to set up the new object. How those parameters are used depends on the object and what the particular init method does.
In your case, you are calling an init method initWithMessage:firstChoice:secondChoice:firstPice:secondPiece:isEnd:
It looks like it takes a message string, 2 choice strings, 2 piece objects, and a BOOL value.
The header for that class should include information about how the different parameters are used.
Regards,
Duncan C WareTo
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In that document, what I refer to is in one place called member variable declaration.
I find it a fitting name when declaring a data type or object inside a class - cause it becomes a member of that class. It´s just how my mind organizes these concepts wich are still a bit abstract to me. But getting there.
So.. I understand that the firstChoice secondChoice etc... is a part of initWithMessage method, makes sense.
In that document, what I refer to is in one place called member variable declaration.
I find it a fitting name when declaring a data type or object inside a class - cause it becomes a member of that class. It´s just how my mind organizes these concepts wich are still a bit abstract to me. But getting there.
So.. I understand that the firstChoice secondChoice etc... is a part of initWithMessage method, makes sense.
Member variables, or instance variables, as I prefer to call them, are variables that belong to an instance of a class.
The variables do not become a "member of that class". The term member means something very specific in Object Oriented programming, and you are using it totally wrong.
You are going to get very confused if you think of it that way. A member of a class is an INSTANCE of a class.
Imagine a car class.
You call the car factory and ask for a car. You ask for a blue convertible with a 6 cylinder engine. The settings you ask for are parameters to the init method. The car factory creates an instance of a car object (or a member of the car class) and passes it back to you. It installs the settings you provide into the instance variables of that car. Somebody else's car will have different options, so another car will have different values for it's instance variables.
There might also be instance variables for the amount of gas in the tank, the setting on the radio, etc. The CD player might also have a CD object installed in it. (A "has a" relationship", where the car's CD player "has a" CD).
Regards,
Duncan C WareTo
Animated GIF created with Face Dancer, available for free in the app store.
Murphy
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I suggest this link as a starting point:
https://developer.apple.com/library/ios/#referencelibrary/GettingStarted/Learning_Objective-C_A_Primer/_index.html
In a nutshell:
Creating an objective C object is a 2 step process. You use alloc to create the storage for an object. You then send an init message to the newly allocated object to get it to set itself up for use. You must send an init method to every object before you can use it.
Init methods come in different flavors. Some init methods don't take any parameters. Some take one or more.
When you call an init method with multiple parameters, you are providing extra information that is used by the init method to set up the new object. How those parameters are used depends on the object and what the particular init method does.
In your case, you are calling an init method initWithMessage:firstChoice:secondChoice:firstPice:secondPiece:isEnd:
It looks like it takes a message string, 2 choice strings, 2 piece objects, and a BOOL value.
The header for that class should include information about how the different parameters are used.
Duncan C
WareTo
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0 • Off Topic Insightful Disagree Dislike Like AwesomeI find it a fitting name when declaring a data type or object inside a class - cause it becomes a member of that class. It´s just how my mind organizes these concepts wich are still a bit abstract to me. But getting there.
So.. I understand that the firstChoice secondChoice etc... is a part of initWithMessage method, makes sense.
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0 • Off Topic Insightful Disagree Dislike Like AwesomeThe variables do not become a "member of that class". The term member means something very specific in Object Oriented programming, and you are using it totally wrong.
You are going to get very confused if you think of it that way. A member of a class is an INSTANCE of a class.
Imagine a car class.
You call the car factory and ask for a car. You ask for a blue convertible with a 6 cylinder engine. The settings you ask for are parameters to the init method. The car factory creates an instance of a car object (or a member of the car class) and passes it back to you. It installs the settings you provide into the instance variables of that car. Somebody else's car will have different options, so another car will have different values for it's instance variables.
There might also be instance variables for the amount of gas in the tank, the setting on the radio, etc. The CD player might also have a CD object installed in it. (A "has a" relationship", where the car's CD player "has a" CD).
Duncan C
WareTo
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0 • Off Topic Insightful Disagree Dislike Like Awesome