Blocks with closures errors in Obj-C

gistfile1.m

@interface TestClass : NSObject {
#if NS_BLOCKS_AVAILABLE
	void (^blk)(void);
#endif
}
- (id)initWithBlock:(void (^)(void))block;
- (void)exec;
@end

@implementation TestClass
#if NS_BLOCKS_AVAILABLE
- (id)initWithBlock:(void (^)(void))block {
	if ((self = [super init])) {
		blk = Block_copy(block);
	}
	return self;
}
- (void)exec {
	if (blk) blk();
}
- (void)dealloc {
	Block_release(blk);
	[super dealloc];
}
#endif
@end

// app code:

// ################################
// refer instance in the block -
// ERROR on Block_copy(block);
// EXC_BAD_ACCESS
// debugger on: 0x000023b2  <+0050>  add    $0x18,%esp
// stack trace is on: Block_copy(block);
// ################################

TestClass *test1 = [[TestClass alloc] initWithBlock:^{
	NSLog(@"TestClass %@", test1);
}];
[test1 exec];
[test1 release];


// ################################
// alloc instance BEFORE init
// NO ERROR
// ################################

TestClass *test2 = [TestClass alloc];
test2 = [test2 initWithBlock:^{
	NSLog(@"TestClass %@", test2);
}];
[test2 exec];
[test2 release];