如果结构不适用于NSDate验证

Question

这是我的代码，用于检查两个NSDate对象是否有值，但问题是这个结构不起作用，我尝试将if语句更改为例如oldDate == nil，但那也不是，工作。有什么想法吗？

if (!oldDate && !newDate) { 
     NSLog(@"oldDate & newDate are empty"); 
    } 
    else { 
     NSLog(@"oldDate & newDate have values"); 
    } 

    if (!oldDate) { 
     NSLog(@"oldDate is empty but newDate has a value"); 
    } 
    else if (!newDate) { 
     NSLog(@"newDate is empty but oldDate has a value"); 
    } 

Answer 1

你有两个if/else块被执行。但你想只有一个：

if (!oldDate && !newDate) { 
    NSLog(@"oldDate & newDate are empty"); 
} else if (!oldDate) { 
    NSLog(@"oldDate is empty but newDate has a value"); 
} else if (!newDate) { 
    NSLog(@"newDate is empty but oldDate has a value"); 
} else { 
    NSLog(@"oldDate & newDate have values"); 
}