Objective-C基础夯实篇——NSValue&NSNumber(装箱和拆箱)

概述

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NSNumber和NSValue都是用来做装箱用的，把基本类型的数据装成对象。官方文档给的资料说明地很清楚： 

/*	NSValue.h
	Copyright (c) 1994-2014, Apple Inc. All rights reserved.
*/

#import <Foundation/NSObject.h>

@class NSString, NSDictionary;

@interface NSValue : NSObject <NSCopying, NSSecureCoding>

- (void)getValue:(void *)value;
@property (readonly) const char *objCType NS_RETURNS_INNER_POINTER;

- (instancetype)initWithBytes:(const void *)value objCType:(const char *)type NS_DESIGNATED_INITIALIZER;
- (instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;

@end

@interface NSValue (NSValueCreation)

+ (NSValue *)valueWithBytes:(const void *)value objCType:(const char *)type;
+ (NSValue *)value:(const void *)value withObjCType:(const char *)type;

@end

@interface NSValue (NSValueExtensionMethods)

+ (NSValue *)valueWithNonretainedObject:(id)anObject;
@property (nonatomic, readonly) id nonretainedObjectValue;

+ (NSValue *)valueWithPointer:(const void *)pointer;
- (void *)pointerValue;

- (BOOL)isEqualToValue:(NSValue *)value;

@end

@interface NSNumber : NSValue

- (instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithChar:(char)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithUnsignedChar:(unsigned char)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithShort:(short)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithUnsignedShort:(unsigned short)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithInt:(int)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithUnsignedInt:(unsigned int)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithLong:(long)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithUnsignedLong:(unsigned long)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithLongLong:(long long)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithUnsignedLongLong:(unsigned long long)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithFloat:(float)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithDouble:(double)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithBool:(BOOL)value NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithInteger:(NSInteger)value NS_AVAILABLE(10_5, 2_0) NS_DESIGNATED_INITIALIZER;
- (NSNumber *)initWithUnsignedInteger:(NSUInteger)value NS_AVAILABLE(10_5, 2_0) NS_DESIGNATED_INITIALIZER;

@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;

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

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

- (NSString *)descriptionWithLocale:(id)locale;

@end

@interface NSNumber (NSNumberCreation)

+ (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);

@end

本文主要内容如下：

　　1.文档说明

      2.测试程序

文档说明

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NSNumber是继承自NSValue的。NSValue可以装任意值，NSNumber主要用于处理我们常用的基本数据类型。NSValue的用法还需要待学习深入。 

NSNumber有快速语法：使用@     比如@YES 就可以封装成对象了。具体在测试程序中有说明。

测试程序

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//
//  main.m
//  NSNumber&NSValue
//
//  Created by hushunfengMac-CMCC on 15/7/8.
//  Copyright (c) 2015年 hushunfengMac-CMCC. All rights reserved.
//

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // insert code here...
        NSNumber *intNum = [NSNumber numberWithInt:10];
        int i = intNum.intValue;
        NSLog(@"%d",i);
        
        
        //快速语法
        NSNumber *boolNum = @YES;
        BOOL x = boolNum.boolValue;
        BOOL y = [boolNum boolValue];
        
        NSLog(@"%i",x);
        NSLog(@"%i",y);
        
        //NSLog(@"Hello, World!");
    }
    return 0;
}