NSNumber基本用法

NSNumber is a subclass of NSValue that offers a value as any C scalar (numeric) type. It defines a set of methods specifically for setting and accessing the value as a signed or unsignedchar, short int,int, long int,long long int, float, ordouble or as a BOOL. (Note that number objects do not necessarily preserve the type they are created with.) It also defines acompare: method to determine the ordering of twoNSNumber objects.

#import <Foundation/Foundation.h>int main(int argc, const char * argv[]) {    @autoreleasepool {        /* NSArray用于NSObject对象的集合，为了能使用基本类型，需要通过NSNumber转换 */        NSNumber *intNum1 = [[NSNumber alloc] initWithInt: 1];        NSNumber *intNum2 = [[NSNumber alloc] initWithInt: 2];        NSNumber *charNum1 = [[NSNumber alloc] initWithChar: 'A'];        NSNumber *floatNum1 = [[NSNumber alloc] initWithFloat: 1.2];        NSNumber *doubleNum1 = [[NSNumber alloc] initWithDouble: 3.4];        NSArray *arr = [[NSArray alloc] initWithObjects: intNum1, intNum2, charNum1,                        floatNum1, doubleNum1, nil];        NSLog(@"arr is:%@", arr);                /* 比较 */        BOOL ret = [intNum1 isEqualToNumber: intNum2];        NSLog(@"ret:%d", ret);        NSComparisonResult result = [intNum1 compare:intNum2];        if (result == NSOrderedAscending)        {            NSLog(@"<");        }        else if (result == NSOrderedSame)        {            NSLog(@"==");        }        if (result == NSOrderedDescending)        {            NSLog(@">");        }                /* 从NSNumber中获取基本类型值 */        int a = [intNum1 intValue];        float b = [floatNum1 floatValue];        char c = [charNum1 charValue];        double d = [doubleNum1 doubleValue];        NSLog(@"%d,%f,%c,%lf", a,b,c,d);    }    return 0;}

输出结果：

2015-11-24 22:29:37.356 TestNSNumber[485:12892] arr is:(    1,    2,    65,    "1.2",    "3.4")2015-11-24 22:29:37.356 TestNSNumber[485:12892] ret:02015-11-24 22:29:37.356 TestNSNumber[485:12892] <2015-11-24 22:29:37.357 TestNSNumber[485:12892] 1,1.200000,A,3.400000