objective-c - 我如何确定是否从 -valueForKey : was initially an int or float? 返回的 NSNumber

Question

原因是我必须取回属性中的确切值。所以如果它是一个 float ，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 是与 CFNumber 桥接的免费电话(除其他来源外，请参阅 CFNumber reference 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在没有复杂性的情况下，似乎可以完全按照您的意愿行事。所以:

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