如何使用NSMutableArray对sortedArrayUsingDescriptors进行排序？
如何使用NSMutableArray对sortedArrayUsingDescriptors进行排序？
提问于 2009-12-04 00:16:21
我有一个关于NSMutableArray排序的问题。我可以使用sortedArrayUsingDescriptors:方法对带有对象的数组进行排序。
例如，我有一个属性NSMutableArray of places，其中有一个属性frequency (int值)，我想在frequency上排序，但是我不知道如何正确地使用它。
我在initWithKey**?** 中把什么作为密钥
我的对象place包含：
NSString * name;
NSString * address;
NSString * frequency;
NSString * type;NSMutableArray * places;
... populate array with objects ...
NSSortDescriptor * sortByFrequency =
[[[NSSortDescriptor alloc] initWithKey:@"????????" ascending:NO] autorelease];
NSArray * descriptors = [NSArray arrayWithObject:sortByFrequency];
NSArray * sorted = [x sortedArrayUsingDescriptors:descriptors];回答 3
Stack Overflow用户
发布于 2009-12-04 06:08:11
若要对对象数组进行排序，请执行以下操作：
- 安装
NSSortDescriptor-使用变量的名称作为设置描述符的键，用于排序，再加上要在这些键上执行的选择器。 - 使用您设置的
NSSortDescriptor获取描述符数组 - 根据这些描述符对数组进行排序
这里有两个示例，一个使用NSDictionary和NSString/NSNumber值在NSNumber上排序，另一个使用自定义类对两个NSString字段进行排序。
遵循Cocoa编程主题中的对NSArray对象进行排序和过滤，查看更多的示例和解释。
示例
这是在GNUStep上完成的，它在Cocoa上的工作应该是一样的--代码完全相同--当我坐在Mac前面时，我会尝试：
使用NSString 和 NSNumber 值对 NSNumber 值进行排序的第一个示例：
NSString * NAME = @"name";
NSString * ADDRESS = @"address";
NSString * FREQUENCY = @"frequency";
NSString * TYPE = @"type";
NSMutableArray * array = [NSMutableArray array];
NSDictionary * dict;
dict = [NSDictionary dictionaryWithObjectsAndKeys:
@"Alehandro", NAME, @"Sydney", ADDRESS,
[NSNumber numberWithInt:100], FREQUENCY,
@"T", TYPE, nil];
[array addObject:dict];
dict = [NSDictionary dictionaryWithObjectsAndKeys:
@"Xentro", NAME, @"Melbourne", ADDRESS,
[NSNumber numberWithInt:50], FREQUENCY,
@"X", TYPE, nil];
[array addObject:dict];
dict = [NSDictionary dictionaryWithObjectsAndKeys:
@"John", NAME, @"Perth", ADDRESS,
[NSNumber numberWithInt:75],
FREQUENCY, @"A", TYPE, nil];
[array addObject:dict];
dict = [NSDictionary dictionaryWithObjectsAndKeys:
@"Fjord", NAME, @"Brisbane", ADDRESS,
[NSNumber numberWithInt:20], FREQUENCY,
@"B", TYPE, nil];
[array addObject:dict];使用描述符和频率场( NSNumber )对零件排序
NSSortDescriptor * frequencyDescriptor =
[[[NSSortDescriptor alloc] initWithKey:FREQUENCY
ascending:YES] autorelease];
id obj;
NSEnumerator * enumerator = [array objectEnumerator];
while ((obj = [enumerator nextObject])) NSLog(@"%@", obj);
NSArray * descriptors =
[NSArray arrayWithObjects:frequencyDescriptor, nil];
NSArray * sortedArray =
[array sortedArrayUsingDescriptors:descriptors];
NSLog(@"\nSorted ...");
enumerator = [sortedArray objectEnumerator];
while ((obj = [enumerator nextObject])) NSLog(@"%@", obj);输出-按频率场排序：
2009-12-04 x[1] {address = Sydney; frequency = 100; name = Alehandro; type = T; }
2009-12-04 x[1] {address = Melbourne; frequency = 50; name = Xentro; type = X; }
2009-12-04 x[1] {address = Perth; frequency = 75; name = John; type = A; }
2009-12-04 x[1] {address = Brisbane; frequency = 20; name = Fjord; type = B; }
2009-12-04 x[1]
Sorted ...
2009-12-04 x[1] {address = Brisbane; frequency = 20; name = Fjord; type = B; }
2009-12-04 x[1] {address = Melbourne; frequency = 50; name = Xentro; type = X; }
2009-12-04 x[1] {address = Perth; frequency = 75; name = John; type = A; }
2009-12-04 x[1] {address = Sydney; frequency = 100; name = Alehandro; type = T; }带有自定义类并对两个NSString 变量进行排序的第二个示例。
数组进行排序(请参见底部的类A )：
NSMutableArray * array = [NSMutableArray array];
[array addObject:[[A alloc] initWithFirstName:@"Alehandro"
lastName:@"Xentro"
age:[NSNumber numberWithInt:40]]];
[array addObject:[[A alloc] initWithFirstName:@"John"
lastName:@"Smith"
age:[NSNumber numberWithInt:30]]];
[array addObject:[[A alloc] initWithFirstName:@"John"
lastName:@"Smyth"
age:[NSNumber numberWithInt:25]]];
[array addObject:[[A alloc] initWithFirstName:@"Torro"
lastName:@"Ola"
age:[NSNumber numberWithInt:45]]];
[array addObject:[[A alloc] initWithFirstName:@"Alehandro"
lastName:@"Bento"
age:[NSNumber numberWithInt:41]]];
[array addObject:[[A alloc] initWithFirstName:@"Alehandro"
lastName:@"Axel"
age:[NSNumber numberWithInt:41]]];排序部分，在lastName上排序，然后在firstName上排序：
NSString * LASTNAME = @"lastName";
NSString * FIRSTNAME = @"firstName";
NSSortDescriptor *lastDescriptor =
[[[NSSortDescriptor alloc]
initWithKey:LASTNAME
ascending:YES
selector:@selector(localizedCaseInsensitiveCompare:)] autorelease];
NSSortDescriptor *firstDescriptor =
[[[NSSortDescriptor alloc]
initWithKey:FIRSTNAME
ascending:YES
selector:@selector(localizedCaseInsensitiveCompare:)] autorelease];
NSArray * descriptors =
[NSArray arrayWithObjects:lastDescriptor, firstDescriptor, nil];
NSArray * sortedArray =
[array sortedArrayUsingDescriptors:descriptors];打印结果：
NSLog(@"\nSorted ...");
enumerator = [sortedArray objectEnumerator];
while ((obj = [enumerator nextObject])) NSLog(@"%@", obj);结果(排序前后)：
2009-12-04 00:52:16.637 x[11375] Alehandro, Xentro, age:40
2009-12-04 00:52:16.644 x[11375] John, Smith, age:30
2009-12-04 00:52:16.644 x[11375] John, Smyth, age:25
2009-12-04 00:52:16.644 x[11375] Torro, Ola, age:45
2009-12-04 00:52:16.645 x[11375] Alehandro, Bento, age:41
2009-12-04 00:52:16.645 x[11375] Alehandro, Axel, age:41
2009-12-04 00:52:16.645 x[11375]
Sorted ...
2009-12-04 00:52:16.645 x[11375] Alehandro, Axel, age:41
2009-12-04 00:52:16.645 x[11375] Alehandro, Bento, age:41
2009-12-04 00:52:16.645 x[11375] Torro, Ola, age:45
2009-12-04 00:52:16.645 x[11375] John, Smith, age:30
2009-12-04 00:52:16.645 x[11375] John, Smyth, age:25
2009-12-04 00:52:16.645 x[11375] Alehandro, Xentro, age:40类A扩展了NSObject -在这里没有什么特别的：
#import <Foundation/Foundation.h>
@interface A : NSObject
{
NSString * firstName;
NSString * lastName;
NSNumber * age;
}
- (id)initWithFirstName:(NSString*)aFirstName
lastName:(NSString*)aLastName
age:(NSNumber*)anAge;
-(NSString* )description;
+(NSString*)action;
@end执行情况：
#import <Foundation/Foundation.h>
#import "A.h"
@implementation A
- (id)init
{
return [self initWithFirstName:@"N/A"
lastName:@"N/A"
age:0];
}
- (id)initWithFirstName:(NSString*)aFirstName
lastName:(NSString*)aLastName
age:(NSNumber*)anAge
{
self = [super init];
if (!self) return nil;
firstName = [aFirstName copy];
lastName = [aLastName copy];
age = [anAge copy];
return self;
}
- (void)dealloc
{
[firstName release];
[lastName release];
[age release];
[super release];
}- (NSString *) description
{
return [NSString stringWithFormat: @"%@, %@, age:%@",
firstName, lastName, age];
}
@endStack Overflow用户
发布于 2009-12-04 00:44:19
"key“是对象的一个方法(数组”x“中的元素)，它返回要排序的内容。所以在这个例子中，你说你想按“频率”排序。然后，您要做的就是使用返回频率的方法的名称作为键。
Stack Overflow用户
发布于 2009-12-04 00:34:56
下面是如何对NSMutableArray进行排序的方法：
NSMutableArray *numberSort =[[NSMutableArray alloc] init];
while ((key = [enumerator nextObject])) {
//(NSNumber *)integer = [key integerValue];
[numberSort addObject:[NSNumber numberWithInt:[key intValue]]];
// code that uses the returned key
}
NSArray *stringSort = [numberSort sortedArrayUsingSelector:@selector(compare:)];
enumerator = [stringSort objectEnumerator];
NSNumber *intKey;
NSMutableArray *backToString =[[NSMutableArray alloc] init];
while ((intKey = [enumerator nextObject])) {
//(NSNumber *)integer = [key integerValue];
[backToString addObject:[intKey stringValue]];
// code that uses the returned key 页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/1844031
复制相关文章
相似问题
腾讯云开发者
