CODEWITHSUNDEEP
xcodeios5automatic-ref-counting
ICL1901
ICL1901

Reputation: 7778

Converting iOS5 app to ARC

I am integrating some third party code into my app, and at the same time, trying to convert the app to ARC.

I'm attaching a screen shot to show the only two errors. If this is obvious to someone how to recode this section, I would be most grateful.

enter image description here

I have one more pita to solve. What's the most pragmatic way to solve this one:

value =  (NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(kCFAllocatorDefault,
                                                                                             (CFStringRef)value,
                                                                                             CFSTR(" "),
                                                                                             kCFStringEncodingUTF8);

This gives this error:

"Cast of Objective-C pointer type 'NSString *' to C pointer type 'CFStringRef' (aka 'const struct __CFString *') requires a bridged cast"

Thanks again.. I will lose this code asap...

Upvotes: 0

Views: 1359

Answers (3)

Fabian Kreiser
Fabian Kreiser

Reputation: 8337

You shouldn't use -performSelector: anyway. Use objc_msgSend(target, selector, ...) instead. If you call -respondsToSelector: you can just use [vc setDelegate:self.delegate] after the if-statement. The same is true for the first line. Replace it with:

UIViewController *vc = [vcClass alloc]; // vc = [[vcClass alloc] initWithSomething:[specifier file] ...]; if the initSelector is known at compile time

If the initSelector is dynamically generated:

objc_msgSend(vc, initSelector, [specifier file], ...);

Hope this helps.

Update: Answer to the second question

If you transfer CF objects to Objective-C objects, ARC needs to know how the memory management is handled. You have to insert __bridge, __bridge_retained or __bridge_transfer before the cast:

NSString *value;
value = (__bridge_transfer NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(kCFAllocatorDefault, (__bridge CFStringRef)value, CFSTR(" "), kCFStringEncodingUTF8);

You use __bridge if you only want to cast between CF and Objective-C, __bridge_retained if it's a retained value and you handle that later using CFRelease and __bridge_transfer if you want to transfer the object from CF to Objective-C or vice-versa.

Upvotes: 2

justin
justin

Reputation: 104698

You should use normal objc messaging, rather than performSelector: all over the place like that.

As well, you should:

  • set vc to the result of the initializer.
  • not need to message release (or call [obj performSelector:@selector(release)];) in an ARC program - the compiler will handle that for you.

One final underlying problem is that the initializer should not use a selector like that. If you really need that form, consider using/passing a convenience constructor instead of an initialization selector.

Upvotes: 1

Psycho
Psycho

Reputation: 1883

The only reason you'd ever use performSelector: is when the selector is dynamically generated, if you know what selector you are going to use, then you should use it, so performSelector:@selector(alloc) makes absolutely no sense.

Upvotes: 1

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