Objective-C Numbers/数字 - Objective-C教程

在Objective-C编程语言，为了保存的基本数据类型，如整型，浮点型，布尔对象的形式，

Objective-C中提供了一系列的NSNumber和重要的工作方法是下表中列出。

S.N. 方法和说明
1 + (NSNumber *)numberWithBool:(BOOL)value Creates and returns an NSNumber object containing a given value, treating it as a BOOL.
2 + (NSNumber *)numberWithChar:(char)value Creates and returns an NSNumber object containing a given value, treating it as a signed char.
3 + (NSNumber *)numberWithDouble:(double)value Creates and returns an NSNumber object containing a given value, treating it as a double.
4 + (NSNumber *)numberWithFloat:(float)value Creates and returns an NSNumber object containing a given value, treating it as a float.
5 + (NSNumber *)numberWithInt:(int)value Creates and returns an NSNumber object containing a given value, treating it as a signed int.
6 + (NSNumber *)numberWithInteger:(NSInteger)value Creates and returns an NSNumber object containing a given value, treating it as an NSInteger.
7 - (BOOL)boolValue Returns the receiver's value as a BOOL.
8 - (char)charValue Returns the receiver's value as a char.
9 - (double)doubleValue Returns the receiver's value as a double.
10 - (float)floatValue Returns the receiver's value as a float.
11 - (NSInteger)integerValue Returns the receiver's value as an NSInteger.
12 - (int)intValue Returns the receiver's value as an int.
13 - (NSString *)stringValue Returns the receiver's value as a human-readable string.

下面是一个简单的例子，使用的NSNumber两个数字相乘，并返回该产品。

#import <Foundation/Foundation.h>

@interface SampleClass:NSObject

- (NSNumber *)multiplyA:(NSNumber *)a withB:(NSNumber *)b;

@end

@implementation SampleClass

- (NSNumber *)multiplyA:(NSNumber *)a withB:(NSNumber *)b
{
   float number1 = [a floatValue];
   float number2 = [b floatValue];
   float product = number1 * number2;
   NSNumber *result = [NSNumber numberWithFloat:product];
   return result;
}

@end

int main()
{
   NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

   SampleClass *sampleClass = [[SampleClass alloc]init];
   NSNumber *a = [NSNumber numberWithFloat:10.5];
   NSNumber *b = [NSNumber numberWithFloat:10.0];   
   NSNumber *result = [sampleClass multiplyA:a withB:b];
   NSString *resultString = [result stringValue];
   NSLog(@"The product is %@",resultString);

   [pool drain];
   return 0;
}

现在，当我们编译并运行程序，我们会得到以下的结果。

2013-09-14 18:53:40.575 demo[16787] The product is 105