ObjectiveC - NSNumber

oc中把 int，double 这些表示数字的数据类型单独封装成NSNumber类

         NSNumber *numInt = [NSNumber numberWithInt:10];            //两种初始化方式1         NSNumber *numFloat = [[NSNumber alloc] initWithFloat:10.8];//两种初始化方式2         NSLog(@"numInt : %@", numInt);         NSLog(@"numFloat : %@", numFloat);         // chart 会转换成ascii码         NSNumber *numChar =  [NSNumber numberWithChar:'a'];         NSLog(@"numChar : %@", numChar);         // 还原成基本数据类型         int i = [numInt intValue];         float f = [numFloat floatValue];         NSLog(@"int : %d", i);         NSLog(@"float : %.1f", f);