NSNumber简单介绍

NSNumber是数字的对象形式,由于在OC的数组和字典中仅仅同意存放对象,所以我们有时候须要转化

我们普通的类型是   123 那么 NSNumber类型的是  @123,它是一个对象

1.把int float double等类型转化为 NSNumber类型

查看系统的API我们能够看见有例如以下的方法能够生成NSNumber类型:

+ (NSNumber *)numberWithChar:(char)value;

+ (NSNumber *)numberWithUnsignedChar:(unsigned char)value;

+ (NSNumber *)numberWithShort:(short)value;

+ (NSNumber *)numberWithUnsignedShort:(unsigned short)value;

+ (NSNumber *)numberWithInt:(int)value;

+ (NSNumber *)numberWithUnsignedInt:(unsigned int)value;

+ (NSNumber *)numberWithLong:(long)value;

+ (NSNumber *)numberWithUnsignedLong:(unsigned long)value;

+ (NSNumber *)numberWithLongLong:(long long)value;

+ (NSNumber *)numberWithUnsignedLongLong:(unsigned long long)value;

+ (NSNumber *)numberWithFloat:(float)value;

+ (NSNumber *)numberWithDouble:(double)value;

+ (NSNumber *)numberWithBool:(BOOL)value;

+ (NSNumber *)numberWithInteger:(NSInteger)value NS_AVAILABLE(10_5, 2_0);

+ (NSNumber *)numberWithUnsignedInteger:(NSUInteger)value NS_AVAILABLE(10_5, 2_0);

使用演示样例:

        //1.把 int float double转化为相应的对象类

        int aa1 = 110;

        NSNumber *aa2 = @(aa1);//直接使用@符号转化

        NSNumber *aa3 = [NSNumber numberWithInt:aa1];//用法转化

        float bb1 = 13.4;

        NSNumber *bb2 = [NSNumber numberWithFloat:bb1];

        NSLog(@"aa2 = %@,bb2 = %@",aa2,bb2);

2.把 NSNumber转化为普通数据类型

我们能够通过NSNumber的属性和方法来获得其内部的值

@property (readonly) char charValue;

@property (readonly) unsigned char unsignedCharValue;

@property (readonly) short shortValue;

@property (readonly) unsigned short unsignedShortValue;

@property (readonly) int intValue;

@property (readonly) unsigned int unsignedIntValue;

@property (readonly) long longValue;

@property (readonly) unsigned long unsignedLongValue;

@property (readonly) long long longLongValue;

@property (readonly) unsigned long long unsignedLongLongValue;

@property (readonly) float floatValue;

@property (readonly) double doubleValue;

@property (readonly) BOOL boolValue;

@property (readonly) NSInteger integerValue NS_AVAILABLE(10_5, 2_0);

@property (readonly) NSUInteger unsignedIntegerValue NS_AVAILABLE(10_5, 2_0);

@property (readonly, copy) NSString *stringValue;

使用演示样例:

   //2.获取NSNumber中的数字值

        NSNumber *cc1 = @123;

        int cc2 = [cc1 intValue];//获取整数值

        NSNumber *dd1 = @123.456;

        double dd2 = [dd1 doubleValue];//获取double值

        double dd3= dd1.intValue;//属性方式

3.NSNumber之间的比較

- (NSComparisonResult)compare:(NSNumber *)otherNumber;

- (BOOL)isEqualToNumber:(NSNumber *)number;

4.NSNumber存放到 数组 或者 字典中

        NSArray *arr = @[@1,@123,@2];

        NSNumber *num1 = arr[0];

        NSNumber *num2 = [arr objectAtIndex:1];

        NSDictionary *dic = @{@"key1":@1,@"key2":@2};

        NSNumber *nu1 = dic[@"key1"];

        NSNumber *nu2 = [dic objectForKey:@"key2"];