missing block__type specifier error.

[nick.keroulis]

I have made a custom class named Box and also an array
called boxes full of Box objects.

Box *newBox;

if (something)
{
    newBox = [boxes objectAtIndex:0];
}

Box *newBox;

if (something)
{
    newBox = (Box *)[boxes objectAtIndex:0];
}

The code above throws the error: "missing block__type specifier".

[RickSDK]

where is the code that you declare "boxes" and add your objects to it?

[Duncan C]

Originally Posted by nick.keroulis

I have made a custom class named Box and also an array
called boxes full of Box objects.

Box *newBox;

if (something)
{
    newBox = [boxes objectAtIndex:0];
}

Box *newBox;

if (something)
{
    newBox = (Box *)[boxes objectAtIndex:0];
}

The code above throws the error: "missing block__type specifier".

Make sure you #import "Box.h" at the top of this .m file, so the compiler knows what a Box object is.

Also, you posted 2 variants of the same code. the second version casts the item from the boxes array to the right type before assigning it to the newBox variable. That's right. The first version lacks the type cast, so the compiler is going to throw a warning.

[nick.keroulis]

Originally Posted by RickSDK

where is the code that you declare "boxes" and add your objects to it?

NSMutableArray *boxes;

I have imported the "Box.h" file.

Also if you have a function like:

-(void)userSmashedBox:(Box *)box
{
   Box *newBox;

   newBox = box;
}

It throws the same error.

[RickSDK]

there's probably something wrong with your box.m file or .h file

[nick.keroulis]

Originally Posted by RickSDK

there's probably something wrong with your box.m file or .h file

What could possibly the error be? The .h, .m files include nothing else than
the standard initialization function. Should i add something else?

.h

#import "Foundation/Foundation.h"

@interface Box : NSObject
{
    UIImage *img;
}
@property (nonatomic, retain) UIImage *img;

-(id)initWithImage:(UIImage *)newImg;

@end

.m

@implementation Box
@synthesize img;

-(id)initWithImage:(UIImage *)newImg
{
   if (self = [super init])
    {
        self.img = newImg;
    }
    
    return self;
}

@end

[JasonR]

The missing semi-colon (; ) on the end of the "return self" line would cause this error.

[nick.keroulis]

Originally Posted by JasonR

The missing semi-colon (; ) on the end of the "return self" line would cause this error.

I misspelled it. Sorry. Actually there is a semicolon.

I can initialize a Box no prob.

Box *box = [[Box alloc] initWithImage:[UIImage imageNamed:@"blue.png"]];

Even this code works:

#import "Foundation/Foundation.h"
#import "Box.h"

@interface ViewController : UIViewController
{
    Box *currentBox;
}
@property (nonatomic, retain) Box *currentBox;

-(void)doSomething;
@end

#import "ViewController.h"

@implementation ViewController
@synthesize currentBox;

-(void)doSomething
{
    Box *anotherBox = [[Box alloc] initWithImage:[UIImage imageNamed:@"blue.png"]];
   currentBox = anotherBox;
}
@end

[nick.keroulis]

Originally Posted by nick.keroulis

I misspelled it. Sorry. Actually there is a semicolon.

I can initialize a Box no prob.

Box *box = [[Box alloc] initWithImage:[UIImage imageNamed:@"blue.png"]];

Even this code works:

#import "Foundation/Foundation.h"
#import "Box.h"

@interface ViewController : UIViewController
{
    Box *currentBox;
}
@property (nonatomic, retain) Box *currentBox;

-(void)doSomething;
@end

#import "ViewController.h"

@implementation ViewController
@synthesize currentBox;

-(void)doSomething
{
    Box *anotherBox = [[Box alloc] initWithImage:[UIImage imageNamed:@"blue.png"]];
   currentBox = anotherBox;
}
@end

But this code DOES NOT work. !!!???

-(void)doSomethingElse:(Box *)box
{
   Box *aBox;
   aBox = box;
}

[BrianSlick]

Is that the exact error message? Are you sure it isn't "missing __block type specifier"?

[nick.keroulis]

Originally Posted by BrianSlick

Is that the exact error message? Are you sure it isn't "missing __block type specifier"?

Yeah!, The error is: "missing__block type specifier".

[BrianSlick]

Precision matters in programming. You've just wasted a lot of time because you did not accurately describe the situation.

Somewhere you are doing a block operation ^{} and messing with a variable that was declared outside the block. You have to prefix with __block in those situations.

[nick.keroulis]

Originally Posted by BrianSlick

Precision matters in programming. You've just wasted a lot of time because you did not accurately describe the situation.

Somewhere you are doing a block operation ^{} and messing with a variable that was declared outside the block. You have to prefix with __block in those situations.

Yes a UIView animate ...

The _block prefix should be added only within the ^{} block?
At every variable? or just the custom ones? When exactly?
When assigning what variables? Why does it exist? Im asking
so many questions when i should google it but i cant find any
documentation on _block prefix. I didn't even knew it existed.

[BrianSlick]

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[Duncan C]

Originally Posted by BrianSlick

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Brian,

I have a block question for you, relating to blocks using/modifying local variables from the scope in which they are invoked.

If I have a local function that declares a variable foo:

__block int foo;

And I define a block inline, I can refer to, and change the value of, foo, within the code of the block. So, if I invoke a system method that takes a block as a parameter, I can have that block use local variables for input, and even write changed values to those local variables.

What if I have a block variable that's defined elsewhere. Can I pass that block variable to a system method, and have the code defined in that block variable read/write values that are defined in the scope where I actually invoke the block? If so, how do I tell the block code about the type of the variable that will exist in the block's lexical scope at the time the block is invoked?

So, in my example, say I'm writing an instance method aMethod that has a local variable foo, defined as __block.

Say I have a block variable called blockOfCode that is defined elsewhere. If in aMethod I pass the block variable blockOfCode to a system function, can blockOfCode access the variable foo which is defined in aMethod?

[BrianSlick]

Not sure, I'm not real strong with blocks myself.

[nick.keroulis]

Originally Posted by Duncan C

Brian,

I have a block question for you, relating to blocks using/modifying local variables from the scope in which they are invoked.

If I have a local function that declares a variable foo:

__block int foo;

And I define a block inline, I can refer to, and change the value of, foo, within the code of the block. So, if I invoke a system method that takes a block as a parameter, I can have that block use local variables for input, and even write changed values to those local variables.

What if I have a block variable that's defined elsewhere. Can I pass that block variable to a system method, and have the code defined in that block variable read/write values that are defined in the scope where I actually invoke the block? If so, how do I tell the block code about the type of the variable that will exist in the block's lexical scope at the time the block is invoked?

So, in my example, say I'm writing an instance method aMethod that has a local variable foo, defined as __block.

Say I have a block variable called blockOfCode that is defined elsewhere. If in aMethod I pass the block variable blockOfCode to a system function, can blockOfCode access the variable foo which is defined in aMethod?

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