将 NSNumber 转换为 NSString 并不是真正的字符串
我在将 NSNumber 值转换为 NSString 时遇到问题，
MyPowerOnOrNot 是一个 NSNumber 女巫，只能返回 1 或 0 并且 myString 是一个 NSString..
myString = [NSString stringWithFormat:@"%d", [myPowerOnOrNot stringValue]];
NSLog(@"%@",myString);
if(myString == @"1") {
[tablearrayPOWERSTATUS addObject:[NSString stringWithFormat:@"%@",@"ON"]];
}
else if(myString == @"0") {
[tablearrayPOWERSTATUS addObject:[NSString stringWithFormat:@"%@",@"OFF"]];
}
这有什么问题？
NSLog 在控制台中将 0 或 1 显示为字符串，但我无法在 if 语句中检查它是 1 还是 0？
如果在实际应该跳入语句时没有跳入语句..我真的不明白为什么这不起作用.. 任何帮助都会非常好！
I have got a problem with converting an NSNumber value to an NSString
MyPowerOnOrNot is an NSNumber witch can only return a 1 or 0
and myString is an NSString..
myString = [NSString stringWithFormat:@"%d", [myPowerOnOrNot stringValue]];
NSLog(@"%@",myString);
if(myString == @"1") {
[tablearrayPOWERSTATUS addObject:[NSString stringWithFormat:@"%@",@"ON"]];
}
else if(myString == @"0") {
[tablearrayPOWERSTATUS addObject:[NSString stringWithFormat:@"%@",@"OFF"]];
}
What is wrong with this?
The NSLog shows 0 or 1 in the console as a string but I can't check it if it is 1 or 0 in an if statement?
If doesn't jump into the statements when it actually should.. I really don't understand why this doesn't works..
Any help would be very nice!
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几个问题
-stringValue 发送到
NSNumber为您提供对字符串的引用。格式说明符%d用于 Cint类型。在这种情况下会发生的是 myString 将包含[myPowerOnOrNot stringValue]返回的 NSString 的地址。或者，在 64 位上，它将返回该地址的一半。实际上，您可以直接使用[myPowerOnOrNot stringValue]并避免相对昂贵的-stringWithFormat:myString和@"1"不一定是同一个对象。您的条件仅检查参考文献是否相同。一般来说，对于 Objective-C，您应该使用-isEqual:来表示对象相等，但我们知道这些是字符串，您可以使用-isEqualToString:或者甚至更好，这样做将 NSNumber 转换为 int 的数字比较。
最后，如果
myPowerOnOrNot不应具有 0 或 1 以外的任何值，请考虑使用一个包罗万象的else来断言或抛出异常，以防万一myPowerOnOrNotcode> 意外地被 bug 设置错误。A couple of problems
-stringValue sent to an
NSNumbergives you a reference to a string. The format specifier%dis for the Cinttype. What would happen in this case is that myString would contain the address of the NSString returned by[myPowerOnOrNot stringValue]. Or, on 64 bit, it would return half of that address. You could actually use[myPowerOnOrNot stringValue]directly and avoid the relatively expensive-stringWithFormat:myStringand@"1"are not necessarily the same object. Your condition only checks that the references are identical. In general with Objective-C you should use-isEqual:for equality of objects, but as we know these are strings, you can use-isEqualToString:Or even better, do a numeric comparison of your NSNumber converted to an int.
Finally if
myPowerOnOrNotis not supposed to have any value other than 0 or 1, consider having a catchallelsethat asserts or throws an exception just in casemyPowerOnOrNotaccidentally gets set wrong by a bug.“myString”是对字符串的引用，而不是字符串本身的值。
== 运算符会将引用与字符串文字进行比较，因此永远不会返回 true。
而是使用
这会将 myString 的值与“1”进行比较
"myString " is a reference to a string, not the value of the string itself.
The == operator will compare the reference to your string literal and so never return true.
Instead use
This will compare the value of myString to "1"
在目标 C 中；您无法使用
==运算符比较字符串是否相等。您在这里要做的就是：
紧凑、快速、美味。
In Objective C; you can't compare strings for equality using the
==operator.What you want to do here is as follows:
Compact, fast, delicious.