objective-c - 如何确定我从 -valueForKey: 返回的 NSNumber 最初是 int 还是 float？

Question

原因是我必须取回财产中的确切价值。所以如果它是一个浮点数，我想调用-floatValue。但如果它是一个 int，我想调用 -intValue。

NSNumber 是否记得它是如何初始化的？

Answer 1

NSNumber 与 CFNumber 是免费桥接的（除其他来源外，请参阅CFNumber 参考顶部的文本）。所以你可以使用CFNumberGetType。例如

- (void)logTypeOf:(NSNumber *)number
{
    switch(CFNumberGetType((CFNumberRef)number))
    {
        case kCFNumberSInt8Type:    NSLog(@"8bit signed integer"); break;
        case kCFNumberSInt16Type:   NSLog(@"16bit signed integer"); break;
        case kCFNumberSInt32Type:   NSLog(@"32bit signed integer"); break;

        /* ... etc, for all of:
           kCFNumberSInt64Type
           kCFNumberFloat32Type
           kCFNumberFloat64Type
           kCFNumberCharType
           kCFNumberShortType
           kCFNumberIntType
           kCFNumberLongType
           kCFNumberLongLongType
           kCFNumberFloatType
           kCFNumberDoubleType
           kCFNumberCFIndexType
           kCFNumberNSIntegerType
           kCFNumberCGFloatType
        */
   }
}

编辑：更彻底地查看文档，CFNumberIsFloatType似乎完全符合您的要求，而且没有复杂性。所以：

if(CFNumberIsFloatType((CFNumberRef)number))
{
    NSLog(@"this was a float");
}
else
{
    NSLog(@"this was an int");
}