NSNumber

1.NSNumber是用来封装基本类型的对象，任何数据封装成NSNumber的时候都可以进行相互比较，或者逻辑运算

2.NSNumber的声明

NSNumber * intNumber = [[[NSNumber alloc] initWithInt:9] autorelease];
NSNumber * floatNumber = [[[NSNumber alloc] initWithFloat:9.0f] autorelease];
NSNumber * doubleNumber = [[[NSNumber alloc] initWithDouble:10] autorelease];       
NSLog(@"%@,%@,%@",intNumber,floatNumber,doubleNumber);
NSLog(@"%d",[intNumber isEqualTo:floatNumber]);

3.将NSNumber转换成基本类型

NSLog(@"%d",[intNumber intValue]);
NSLog(@"%f",[floatNumber floatValue]);
NSLog(@"%f",[doubleNumber doubleValue]);