NSMutableArray containsObject方法不检测对象

Question

// Add the button to the NSMutableArray.
...
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
[[self hBtns] addObject:btn];
...

// In another method, try to see if it exists.
- (void)didPushBtn:(id)sender
{
  UIButton *btn = (UIButton *)sender;
  if ([[self hBtns] containsObject:btn]) // Is false every time.
  ...
}

为什么没有检测到UIButton在数组中？

---

修改

事实证明，它在添加之后甚至都无法检测到它：

UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
[[self hBtns] addObject:btn];
if ([[self hBtns] containsObject:btn]) // Returns false.

Answer 1

听起来isEqual:比较失败了。您是否可以在两个地方（添加它，然后在hash中）查看UIButton的didPushBtn，看看它们是否是相同的值？

Answer 2

我忘了初始化数组（* doh *）：

[self setHBtns:[[NSMutableArray alloc] initWithCapacity:0]];