Objective-C - 比较不按预期工作的整数 [英] Objective-C - Comparing integers not working as expected

问题描述

所以我的问题是：

我从网络上收到一个JSON字符串。解码后（使用SBJSON库），它变成了一个NSDictionary，它应该包含一些关键字'userid'的类型。我说'应该'，因为当我将值与int，NSINTEGER或NSNumber进行比较时，它永远不会正确评估。

I am receiving a JSON string from across the network. When decoded (using SBJSON libraries), it becomes an NSDictionary that SHOULD contain a number of some sort for the key 'userid'. I say 'should' because when I compare the value to an int, or an NSINTEGER, or NSNumber, it never evaluates correctly.

以下是代码中的比较：

NSDictionary *userDictionary = [userInfo objectAtIndex:indexPath.row];

if ([userDictionary objectForKey:@"userid"] == -1) {
 //Do stuff
}

我测试的字典里面的值是-1。当我使用NSLog将其打印到控制台时，它甚至显示为-1。然而，当我在'if'语句中将它与-1进行比较时，如果它应该为真，则计算结果为false。我甚至尝试比较[NSNumber numberWithInt：-1]，它仍然评估为假。

The value inside the dictionary I am testing with is -1. When I print it out to console using NSLog it even shows it is -1. Yet when I compare it to -1 in the 'if' statement, it evaluates to false when it should be true. I've even tried comparing to [NSNumber numberWithInt: -1], and it still evaluates to false.

我做错了什么？在此先感谢您的帮助！

What am I doing wrong? Thanks in advance for your help!

推荐答案

您正在比较指向对象的指针，而不是整数本身。您必须先将对象转换为整数：

You are comparing a pointer to an object, not an integer itself. You must first convert the object into an integer:

if ([[userDictionary objectForKey:@"userid"] integerValue] == -1)
{
     //Do stuff
}

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