OC基础（十四）NSNumber

一、NSNumber：

因为NSArray与NSDictionary中值能存放对象，不能存放基本数据类型，所以需要将基本数据类型转化为对象类型，就用到了NSNumber。同样的对象类型也能转化为基本数据类型，详细代码如下：

 1 #import <Foundation/Foundation.h>
 2 int main(int argc, const char * argv[]) {
 3     @autoreleasepool {
 4         int i = 10;
 5         double d = 3.1;
 6         char c = ‘5‘;
 7         BOOL b = 1;
 8         //基本数据类型转换成对象类型
 9         NSNumber *intNum = [NSNumber numberWithInt:i];
10         NSNumber *doubleNum = [NSNumber numberWithDouble:d];
11         NSNumber *charNum = [NSNumber numberWithChar:c];
12         NSNumber *boolNnum = [NSNumber numberWithBool:b];
13         NSArray *arr = @[intNum,doubleNum,charNum,boolNnum];
14         NSLog(@"%@",arr);
15         //对象类型转化为基本数据类型
16         int ii = [intNum intValue];
17         double dd = [doubleNum doubleValue];
18         char cc = [charNum charValue];
19         BOOL bb = [boolNnum boolValue];
20         NSLog(@"%d %f %c %d",ii,dd,cc,bb);
21         //基本数据类型转化为对象类型的简写
22         NSNumber *num1 = @10;
23         NSNumber *num2 = @(dd);
24         NSLog(@"%@ %@",num1,num2);
25         //注意：当@后面为变量时候一定要加括号，当为常量时候可以省略括号！
26     }
27     return 0;
28 }

输出结果：

1 2016-05-03 10:25:27.367 NSNumber与NSValue[19005:3404888] (
2     10,
3     "3.1",
4     53,
5     1
6 )
7 2016-05-03 10:25:27.368 NSNumber与NSValue[19005:3404888] 10 3.100000 5 1
8 2016-05-03 10:25:27.368 NSNumber与NSValue[19005:3404888] 10 3.1
9 Program ended with exit code: 0