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：

#import <Foundation/Foundation.h>
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        int i = 10;
        double d = 3.1;
        char c = '5';
        BOOL b = 1;
        //基本数据类型转换成对象类型
        NSNumber *intNum = [NSNumber numberWithInt:i];
        NSNumber *doubleNum = [NSNumber numberWithDouble:d];
        NSNumber *charNum = [NSNumber numberWithChar:c];
        NSNumber *boolNnum = [NSNumber numberWithBool:b];
        NSArray *arr = @[intNum,doubleNum,charNum,boolNnum];
        NSLog(@"%@",arr);
        //对象类型转化为基本数据类型
        int ii = [intNum intValue];
        double dd = [doubleNum doubleValue];
        char cc = [charNum charValue];
        BOOL bb = [boolNnum boolValue];
        NSLog(@"%d %f %c %d",ii,dd,cc,bb);
        //基本数据类型转化为对象类型的简写
        NSNumber *num1 = @10;
        NSNumber *num2 = @(dd);
        NSLog(@"%@ %@",num1,num2);
        //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！
    }
    return 0;
}

输出结果：

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