objective-c - sizeof在iPad 1上崩溃但不是> iPad 1

考虑以下代码:

CGFloat largerLineSpacing = kStreamCellParagraphSpacing;

CTParagraphStyleSetting paragraphSettings[1] = {
    { kCTParagraphStyleSpecifierParagraphSpacing, sizeof(CGFloat), &largerLineSpacing }
};
CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(paragraphSettings, sizeof(*paragraphSettings));

在iPad 1(5.1)而不是5.1模拟器或iPad 3(6.0)上运行时，此代码会因EXC_BAD_ACCESS崩溃。我的C很弱-我在用sizeof做一个愚蠢的错误吗？

最佳答案

CTParagraphStyleCreate的文档建议其第二个参数给出CTParagraphStyleSetting数组中paragraphSettings实例的数量(在您的情况下为1)，而不是数组的字节数。

如果您将代码更改为

CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(paragraphSettings, 1);

它应该工作。或者，如果您希望以后再添加更多设置，可以尝试

int numElems = sizeof(paragraphSettings)/sizeof(paragraphSettings[0]);
CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(paragraphSettings,
                                                            numElems);