NSValue

NSNumber实际上是NSValue的子类，NSValue可以封装任意值，使用NSValue可以将结构体放在NSArray或 NSDictionary中，

@interface NSValue (NSValueUIGeometryExtensions)
 
+ (NSValue *)valueWithPointer:(const void *)pointer;//保存对象指针
+ (NSValue *)valueWithCGPoint:(CGPoint)point;//保存CGPoint结构体
+ (NSValue *)valueWithCGSize:(CGSize)size;//保存CGSize结构体
+ (NSValue *)valueWithCGRect:(CGRect)rect;//保存CGRect结构体
+ (NSValue *)valueWithCGAffineTransform:(CGAffineTransform)transform;
+ (NSValue *)valueWithUIEdgeInsets:(UIEdgeInsets)insets;
 
- (void *)pointerValue;
- (CGPoint)CGPointValue;
- (CGSize)CGSizeValue;
- (CGRect)CGRectValue;
- (CGAffineTransform)CGAffineTransformValue;
- (UIEdgeInsets)UIEdgeInsetsValue;
 
@end

 

2.使用介绍

1.自定义的字符

char *p = (char *)0x1f;
NSValue * value = [[NSValue alloc] initWithBytes:&p objCType:@encode(char *)];
char *q;
[value getValue:&q];
 NSLog(@"%p", q);

 2.自定义结构体

#import <Foundation/Foundation.h>

typedef struct {
    int year;
    int month;
    int day;
} Date;

//NSNumber是NSValue的子类，而NSValue可以包装任何类型，包括结构体
void test1(){
    //如果我们自己定义的结构体包装
    Date date={2014,2,28};
    char *type=@encode(Date);
    NSValue *value3=[NSValue value:&date withObjCType:type];//第一参数传递结构体地址，第二个参数传递类型字符串
    NSArray *array2=[NSArray arrayWithObject:value3];
    NSLog(@"%@",array2);
    /*结果：
     (
        "<de070000 02000000 1c000000>"
     )
     */
  
    Date date2;
    [value3 getValue:&date2];//取出对应的结构体，注意没有返回值
    //[value3 objCType]//取出包装内容的类型
    NSLog(@"%i,%i,%i",date2.year,date2.month,date2.day); //结果：2014,2,28
}

int main(int argc, const char * argv[]) 
{
    test1();
    return  0;
}

 

 1.处理NSRange，方法 

+ (NSValue *)valueWithRange:(NSRange)range
- (NSRange)rangeValue
   
NSRange rangeA ;
rangeA.location = 0 ;
rangeA.location = 10 ;

// 创建NSRange的值对象
NSValue *rangeValue = [NSValue valueWithRange:rangeA];
// 重新获取值对象包含的值 
NSRange rangeB = [rangeValue rangeValue] ;
NSLog(@"%d,%d",rangeB.location , rangeB.length) ; // 10,10

2.处理自定义结构体类型，方法 
+ (NSValue *)valueWithBytes:(const void *)value objCType:(const char *)type
- (id)initWithBytes:(const void *)value objCType:(const char *)type
- (void)getValue:(void *)buffer
// 结构体定义
typedef struct{
   int a ;
   float b ;    
}DataItem ;

DataItem dataElemA;
dataElemA.a = 10;
dataElemA.b = 10.005;
    
NSValue *value = [NSValue valueWithBytes:&dataItem objCType:@encode(DataItem)];
DataItem dataElemB;
[value getValue:&dataElemB] ;
NSLog(@"%d,%0.3f",dataElemB.a,dataElemB.b);    // 10,10.005

 

3.结构体对象

// 创建点坐标结构
CGPoint point = CGPointMake(20, 20);
// 将结构体转换成为NSValue对象
NSValue *pointValue = [NSValue valueWithPoint:point];
// 将NSValue对象存放到数组中
NSArray *array = @[pointValue];
// 从数组中取出pointValue对象
NSValue *value = array[0];
// 将NSValue对象转换成为结构体
CGPoint point2 = [value pointValue];    
// 输出:转换成基本类型结构体point2的值：
// 第一种方式：将结构体先转换为字符串然后打印
NSString *str = NSStringFromPoint(point2);
NSLog(@"%@",str); // 输出 {20,20}
// 第二种方式：依次取出对应的值打印
// NSLog(@"%f %f",point2.x,point2.y); 输出 20.000000 20.000000

- (void)viewDidLoad {
    [super viewDidLoad];

    //NSValue包装指针
    NSValue* start = [NSValue valueWithPointer:@selector(start:)];
    NSValue* help = [NSValue valueWithPointer:@selector(help:)];
 
    //NSArray 添加NSValue包装后的指针
    NSArray *Array = [[NSArray alloc] initWithObjects:start, help, nil];
    self.SelectorArray = Array;
 
    CGRect rect1 = {10, 10, 200, 200};
    CGRect rect2 = {20, 20, 100, 100};
 
    //NSValue包装CGRect结构
    NSValue *aRect1 = [NSValue valueWithCGRect:rect1];
    NSValue *aRect2 = [NSValue valueWithCGRect:rect2];
    //NSArray 添加NSValue包装后的指针
    NSArray *reArray = [[NSArray alloc] initWithObjects:aRect1, aRect2, nil];
    self.RectArray = reArray;
 
    //CGAffineTransform
    CGAffineTransform transform1 = CGAffineTransformMakeRotation(40);
    CGAffineTransform transform2 = CGAffineTransformMakeRotation(-40);
    NSValue *aTransform1 = [NSValue valueWithCGAffineTransform:transform1];
    NSValue *aTransform2 = [NSValue valueWithCGAffineTransform:transform2];
    NSArray *TransArray = [[NSArray alloc] initWithObjects:aTransform1, aTransform2, nil];
    self.TransformArray = TransArray;


    [testView setFrame:[[RectArray objectAtIndex:0] CGRectValue]];
    [testView setTransform:[[TransformArray objectAtIndex:0] CGAffineTransformValue]];
    [self performSelector:[[SelectorArray objectAtIndex:0] pointerValue] withObject:nil afterDelay:0.5];    
}
 
-(void)start:(id)sender{
    NSLog(@"start");
    [testView setFrame:[[RectArray objectAtIndex:1] CGRectValue]];
    [testView setTransform:[[TransformArray objectAtIndex:1] CGAffineTransformValue]];
    [self performSelector:[[SelectorArray objectAtIndex:1] pointerValue] withObject:nil afterDelay:0.5];
}
 
-(void)help:(id)sender{
    NSLog(@"help");
    //[testView setFrame:[[RectArray objectAtIndex:0] CGRectValue]];
    //[testView setTransform:[[TransformArray objectAtIndex:0] CGAffineTransformValue]];
}