Question

如何测试objc_getAssociatedObject是nil？以下说元素不是nil，但是之前从未设置过关联对象。

static char orderedElementKey = 11;

if (objc_getAssociatedObject(self, &orderedElementKey) != nil)
{
    NSLog(@"element is not nil");
    return objc_getAssociatedObject(self, &orderedElementKey);
}
NSLog(@"elelement was nil !");

Answer 1

static char orderedElementKey = 11;
//objc_setAssociatedObject(self, &orderedElementKey, @"value", OBJC_ASSOCIATION_RETAIN);

if (objc_getAssociatedObject(self, &orderedElementKey) != nil)
{
    NSLog(@"Element: %@", objc_getAssociatedObject(self, &orderedElementKey));
}
else
{
    NSLog(@"element nil !");
}

打印“Element nil！”删除objc_setAssociatedObject()上的注释时会打印“元素：值”。你的代码有何不同？

if（objc_getAssociatedObject（self，＆amp; Key））为nil对象返回true

1 个答案: