Some extensions to obj-c NSArray class

NSArray+Ext.m

@implementation NSArray(Ext)

-(NSArray*)subarrayWithSize:(int)returnSize
{
    int count = self.count;
    if (returnSize >= 0 && returnSize <= count)
    {
        NSMutableArray *result = [[NSMutableArray alloc] init];
        NSMutableArray *indexes = [NSMutableArray arrayWithCapacity:count];
        for (int i = 0; i < returnSize; i++)
        {
            int ri;
            do {
                ri = arc4random() % count;
            } while ([indexes indexOfObjectIdenticalTo:@(ri)] != NSNotFound);
            result[i] = self[ri];
            [indexes addObject:@(ri)];
        }
        return result;
    } else {
        return nil;
    }
}

-(id)anyObject
{
    return self && self.count > 0 ? self[arc4random() % self.count] : nil;
}

-(NSArray*)reverse
{
    NSMutableArray *newArray = self ? [NSMutableArray arrayWithCapacity:self.count] : nil;
    for (id obj in [self reverseObjectEnumerator])
    {
        [newArray addObject:obj];
    }
    return newArray;
}

-(NSArray*)verifiedObjects:(BOOL(^)(id))verifyingBlock
{
    NSMutableArray *newArray = self ? [NSMutableArray array] : nil;
    for (id obj in self)
    {
        if (verifyingBlock(obj))
        {
            [newArray addObject:obj];
        }
    }
    return newArray;
}

-(BOOL)containsSubArrayEqualsTo:(NSArray*)subArr
{
    for (id obj in self)
    {
        if ([obj isEqualToArray:subArr])
        {
            return TRUE;
        }
    }
    return FALSE;
}

-(NSArray*)extractArrayWithBlock:(id(^)(id))block
{
    NSMutableArray *result = [NSMutableArray array];
    for (id obj in self)
    {
        [result addObject:block(obj)];
    }
    return result;
}

-(NSString*)joinWith:(NSString*)separator
{
    NSMutableString *result = [NSMutableString stringWithString:@""];
    for (id obj in self)
    {
        if (obj == [self lastObject])
        {
            [result appendFormat:@"%@", [obj description]];
        } else {
            [result appendFormat:@"%@%@", [obj description], separator];
        }
    }
    return result;
}

-(int)indexOfObjectMeetsCondition:(BOOL(^)(id))block
{
    for (int i = 0; i < self.count; i++)
    {
        id obj = self[i];
        if (block(obj))
        {
            return i;
        }
    }
    return NSNotFound;
}
@end