一个奇怪的ios 64位问题

Question

我的代码：

- (void)keyboardWillShow:(NSNotification *)notification {

    NSDictionary *userInfo = [notification userInfo];

    NSValue *aValue = [userInfo objectForKey:UIKeyboardFrameBeginUserInfoKey];

    CGRect keyboardRect = [aValue CGRectValue];

    float keyboardHight=keyboardRect.size.height;
}

我在这一行（float keyboardHight=keyboardRect.size.height;）做一个断点，并打印这些变量和结果：

Printing description of userInfo:
{
    UIKeyboardAnimationCurveUserInfoKey = 7;
    UIKeyboardAnimationDurationUserInfoKey = "0.25";
    UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {320, 216}}";
    UIKeyboardCenterBeginUserInfoKey = "NSPoint: {160, 676}";
    UIKeyboardCenterEndUserInfoKey = "NSPoint: {160, 460}";
    UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 568}, {320, 216}}";
    UIKeyboardFrameChangedByUserInteraction = 0;
    UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 352}, {320, 216}}";
}
Printing description of aValue:
NSRect: {{0, 568}, {320, 216}}
Printing description of keyboardRect:
(CGRect) keyboardRect = origin=(x=3.0491553029449835E-314, y=5.6817549271743353E-322) size=(width=3.0509261527954335E-314, height=3.0491551606540775E-314)

为什么[aValue CGRectValue]会返回错误的结果。 它适用于iphone5c但不适用于iphone5s。任何想法都可以。感谢。