objective-c - NSMutableArray containsObject 方法未检测到对象

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？

---

编辑

事实证明，它甚至不会在添加后立即检测到它：

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。你能看看hash两个地方的 UIButton （它被添加的地方，然后在didPushBtn），看看它们是否是相同的值？

Answer 2

我忘记初始化数组（*doh*）：

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