ios - 从数组的中心/中间开始枚举 NSArray 双向搜索

Question

如何枚举从数组中心开始的数组？

Answer 1

@implementation NSArray (Extensions)

- (void)enumerateFromCenterGoBothWaysUsingBlock:(void (^)(id obj, NSUInteger idx, BOOL *stop))block
{
    NSMutableArray *copy = [self mutableCopy];
    BOOL shouldStop = NO;
    while([copy count] > 0 && shouldStop == NO)
    {
        NSUInteger index = [copy count] / 2;
        id obj = copy[index];
        [copy removeObject:obj];

        block(obj, index, &shouldStop);
    }
}

@end