我如何判断我从-valueForKey返回的NSNumber：最初是int还是float？

Question

原因是我必须回到房产中的确切价值。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免费联网（请参阅CFNumber reference顶部的文字，除其他来源外）。所以你可以使用CFNumberGetType。 E.g。

- (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：更详细地查看文档，CFNumberIsFloatType似乎可以完全按照您的要求执行，而不会产生复杂性。所以：

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