I'm new to developing and I'm teaching myself based on tutorials online, and Stanford lectures on iTunesU (I'm only 15).
I'm having two problems with an email form I'm trying to implement into my app. I took a screenshot, here is the link to it: http://tinypic.com/r/2utq05c/5
I've tried everything and just can't seem to get it to work. Any help is GREATLY APPRECIATED.
Thank you.
See that #end line? That ends the class implementation. You can only implement methods within a class implementation—i.e., between the #implementation line and its corresponding #end.
That isn't the only syntax error in that file. You also haven't finished writing your email method, so the method that you have after it is technically within it. Methods can't go within methods, so that's another error. The solution to that one is simply to finish the email method.
Related
I'm working on a open source project, which consist on a framework for iOS devices, and one of the methods is not working as I expected. I tried to search for the implementation of the method, but all I found was a a header file and the method declaration; I didn't find the implementation anywhere. Neither did I find the .m file corresponding to that class.
So I have some questions:
How can a class exist without it's implementation and still its methods perform certain operations?
What is the purpose of writing this kind of classes.
In this kind of situations where should be the methods implemented?
Note
The open source project is FastPdfKit and the method is wholeTextForPage:
Well, those methods are somewhere, so it's not that they don't exist, you just can't see them.
Try for example to open UITableView.h, you can see the methods definition, but not the implementation. The implementation is hidden in the library, but you can't see it.
In a nutshell, developers do this to hide the details of the implementation of a class to other users. You just receive a header that tells you which methods you can use, and how, but the details about how are they implemented are hidden for you.
For example, Apple doesn't want you to see how they implemented UITableView, but they want you to know how you can use it.
Here you can find a tutorial about how to create a library for Objective-C:
Creating Static Libraries for Objective-C
I'm having a problem.
I'm using a code in a testCase
It starts like this
|mapeos obj myClass|
myClass := Smalltalk at: #ClaseForTesting.
myClass addToComposition: TraitPruebaCondicion1.
the #ClaseForTesting is an emptyClass
when smalltalk do
myClass addToComposition: TraitPruebaCondicion1
if I (Debugging) try to get the traits
myClass traits
I'm getting
an OrderedCollection(AnObsoleteTraitPruebaCondicion1)
why is adding AnObsolete in the string trait name?
If I run the same code in workspace, it works really fine.
Why is this happening? any ideas?
Please, its urgent :(
I can't believe that I was stuck with this a lot of time, and then when I FINALLY decided to ask to the people, I've solve it in two minutes. Shame on me. It must be some kind of mystical brainstorming with this site.
Anyway, the clue was to using
Smalltalk at: #
with the trait too! (I was only using it on the class)
so
myClass addToComposition:(Smalltalk at: #TraitPruebaCondicion1).
solve my problem.
I want to create a simple to use and lightweight performance profile framework for Objective C. My goal is to measure the bottlenecks of my application.
Just to mention that I am not a beginner and I am aware of Instruments/Time Profiler. This is not what I am looking for. Time Profiler is a great tool but is too developer oriented. I want a framework that can collect performance data from a QA or pre production users and even incorporate in a real production environment to gather the real data.
The main part of this framework is the ability to measure how much time was spent in Objective C message (I am going to profile only Objective C messages).
The easiest way is to start timer in the beginning of a message and stop it at the end. It is the simplest way but its disadvantage is that it is to tedious and error prone - if any message has more than 1 return path then it will require to add the "stop timer" code before each return.
I am thinking of using method swizzling (just to note that I am aware that Apple are not happy with method swizzling but these profiled builds will be used internally only - will not be uploaded on the App Store).
My idea is to mark each message I want to profile and to generate automatically code for the method swizzling method (maybe using macros). When started, the application will swizzle the original selector with the generated one. The generated one will just start a timer, will call the original method and then will stop the timer. So in general the swizzled method will be just a wrapper of the original one.
One of the problems of the above idea is that I cannot think of an easy way how to automatically generate the methods to use for swizzling.
So I greatly will appreciate if anyone has any ideas how to automate the whole process. The perfect scenario is just to write one line of code anywhere mentioning the class and the selector I want to profile and the rest to be generated automatically.
Also will be very thankful if you have any other idea (beside method swizzling) of how to measure the performance.
I came up with a solution that works for me pretty well. First just to clarify that I was unable to find out an easy (and performance fast) way to automatically generate the appropriate swizzled methods for arbitrary selectors (i.e. with arbitrary arguments and return value) using only the selector name. So I had to add the arguments types and the return value for each selector, not only the selector name. In reality it should be relatively easy to create a small tool that would be able to parse all source files and detect automatically what are the arguments types and the returned value of the selector which we want to profile (and prepare the swizzled methods) but right now I don't need such an automated solution.
So right now my solution includes the above ideas for method swizzling, some C++ code and macros to automate and minimize some coding.
First here is the simple C++ class that measures time
class PerfTimer
{
public:
PerfTimer(PerfProfiledDataCounter* perfProfiledDataCounter);
~PerfTimer();
private:
uint64_t _startTime;
PerfProfiledDataCounter* _perfProfiledDataCounter;
};
I am using C++ to use that the destructor will be executed when object has exited the current scope. The idea is to create PerfTimer in the beginning of each swizzled method and it will take care of measuring the elapsed time for this method
The PerfProfiledDataCounter is a simple struct that counts the number of execution and the whole elapsed time (so it may find out what is the average time spent).
Also I am creating for each class I'd like profile, a category named "__Performance_Profiler_Category" and to conforms to "__Performance_Profiler_Marker" protocol. For easier creating I am using some macros that automatically create such categories. Also I have a set of macros that take selector name, return type and arguments type and create selectors for each selector name.
For all of the above tasks, I've created a set of macros to help me. Also I have a single file with .mm extension to register all classes and all selectors I'd like to profile. On app start, I am using the runtime to retrieve all classes that conforms to "__Performance_Profiler_Marker" protocol (i.e. the registered ones) and search for selectors that are marked for profiling (these selectors starts with predefined prefix). Note that this .mm file is the only file that needs .mm extension and there is no need to change file extension for each class I want to profile.
Afterwards the code swizzles the original selectors with the profiled ones. In each profiled one, I just create PerfTimer and call the swizzled method.
In brief that is my idea which turned out to work pretty smoothly.
I am not even sure how to start.
I am developing an iPhone application with the latest Xcode and sdk using core plot and the core async socket library. Everything was fine until a few hours ago, when Xcode dumped a ton of "interface duplication" errors for no apparent reason.
The two files that are emitting errors are the AsyncSocket.h and an API client that I wrote in order to get data out of the target server.
The errors are the following:
Nested Redefinition error on all enums in AsyncSocket.h and my API client.
Redeclaration of enum on all enumerations in AsyncSocket.h and my API client.
Duplicate interface declaration on the AsyncSocket.h and the API client's interface file.
The error occurred between two builds of the application. NOTHING was changed during that time which is why I can't even begin to think what is causing this.
The API client is a really simple thing, it just uses the async socket to send queries to the server and then return the parsed results in arrays. Nothing complicated, as I am not that into objective c yet.
I wish I could give some more useful information but that is all I have.
i believe your problem results from a simple mistake. In the header file you begin with:
#interface ClassName : SuperclassName
while in the .m file you do:
#interface ClassName ()
When you forget the brackets, the compiler complains.
I hope this helps. Best wishes with your app.
I had this problem and the response above put me on the right track.
I created a new enum record in a .h file I use for all my Constants.
But I forgot to add the semi-colon on the end. This simple little syntax error resulted in some weird and confusing errors appearing on files other than the one which contained the error.
No doubt you've resolved this by now but it might fix someone else's issues in the future.
I also experienced the "Duplicate interface definition" error message and traced it to my having put an "#include xxx.h" in a header (.h) file instead of in the .m file where I intended to put it.
Coming from an Eclipse / Java background, one of my favorite features is the ability to quickly stub out all the methods required by an interface. In Eclipse, I can choose 'Override / implement' from the source menu to generate stub methods for any method of the Interface.
I'd like to do the same thing in Objective-C. For instance, if I declare a class that implements the 'NSCoding' protocol, I'd like to have Xcode automatically generate the methods required to implement this Protocol. It's frustrating to have to look-up and then copy/paste the signatures of the required methods every Protocol that I'm trying to implement.
I've been trying for awhile to find out if this is possible, but haven't found anything promising yet. Is this possible in XCode?
I believe that Accessorizer will do what you want.
Accessorizer will write the encode and decode methods for ivars passed to it (NSCoding protocol and for NSDocument archiving). It will also generate string constants either static or #define with a custom prefix; copyWithZone:; and other things if you need - all from a simple shortcut via Services or from the toolbar. Accessorizer keyed archiving
Not the direсt answer, just hint:
Out of the box XCode can't.
But AppCode can.
It can do this things automatically (with your permission, of course).
If some methods of protocol marked as #required - AppCode will highlight the implementation and suggest to implement this methods.
#optional methods also available to implement automatically (shortcut: control + I).
Your can create scripts for the scripting menu item in AppleScript, Perl, Python, Ruby, or any other scripting language that go in the scripting menu.
Your could place the insertion point in the .m file and have the script look up the corresponding .h file. Locate the protocols supported and so forth...
MacTech ran an article in 2007 Xcode Menu Scripts
Xcode 3.2 will autocomplete known method implementations. In other words, if the method is declared somewhere (for example, in a protocol), when you start to type it in a .m file, Xcode 3.2 will autocomplete the method signature for you. This isn't quite what you asked for, but it is awfully handy.
I'm also looking for a way to generate method stubs for the protocols in my header file. I checked out Accessorizer and it looks to be a handy tool but unless I missed something I didn't find a way to get it to generate method stubs for a protocol.
Eric, If you found another solution please post what you found. It's amazing to me that XCode doesn't already have this built into the IDE.
Since the accepted answer's given link does not work anymore (and is redirected to an ad), here's another good explanation on how to use accessorizer to create protocol method stubs.
Based on AllanCraig's "Create #property, #synthesize & dealloc from Variable Declaration" ruby script, I made one to generate implementation stubs from interface ones: http://pastebin.com/4T2LTBh6
How to use?
Setup the script on your XCode (Shell Script) and assign a shortcut for it (e.g. CMD+5).
Select lines from your interface file in which you want to generate the implementation, and press the hotkey.
Your .m will contain your selected methods.
I know this is an old question but if you'd like to always see the latest definitions just right click on the class in question and Jump to Definition. Here lyes all the current non-deprecated functions so you aren't relying on a 3rd party to stay up to date.
In My case Below style helps me much, In a sense solved my problem.
Suppose you have following method declaration:
+(DBManager*)getSharedInstance;
From Implementation file you start typing +ge and xcode will automatically choose method
+(DBManager*)getSharedInstance;