gistfile1.m

#import <Foundation/Foundation.h>

@implementation NSArray (BlocksTest)

- (void) do:(void (^)(id))aBlock;
{
	[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop)
     {
         aBlock(obj);
     }];
}


- (id) inject:(id)aValue into:(id (^)(id, id))aBlock;
{
    __block id sum = aValue;
    
	[self do:^(id each)
     {
         [sum autorelease];
         sum = [aBlock(sum, each) retain];
     }];
    return [sum autorelease];
}

@end



int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    
	id array = [NSArray arrayWithObjects:@"first", @"second", @"third", nil];
    //	[array do:^(id each){
    //		NSLog(@"%@", each);
    //	}];
    //	
	// crashes, why?
    
	NSLog(@"%@", [array inject:@"" into:^(id concatenation, id element)
                  {
                      id ret = [concatenation stringByAppendingString:element];
                      return ret;
                  }]);
    
	[pool drain];
    return 0;
}