NSArray排序 --- sortedArrayUsingDescriptors

 

Java代码

1. [dataArray sortedArrayUsingFunction: sortDataArrayByModifyFileDate context:NULL];
3. NSInteger sortDataArrayByModifyFileDate(id obj1, id obj2, void *context)
4. {
5. NSString* str1 = (NSString*)obj1;
6. NSString* str2 = (NSString*)obj2;
8. NSString* dateString1 = [[str1 componentsSeparatedByString:@"$"] objectAtIndex:2];
9. NSString* dateString2 = [[str2 componentsSeparatedByString:@"$"] objectAtIndex:2];
10. DLog(@">>>>>str1:%@", dateString1);
11. DLog(@">>>>str2:%@", dateString2);
15. return ([dateString2 compare:dateString1]);
16. }

 [dataArray sortedArrayUsingFunction: sortDataArrayByModifyFileDate context:NULL];NSInteger sortDataArrayByModifyFileDate(id obj1, id obj2, void *context){NSString* str1 = (NSString*)obj1;NSString* str2 = (NSString*)obj2;NSString* dateString1 = [[str1 componentsSeparatedByString:@"$"] objectAtIndex:2];NSString* dateString2 = [[str2 componentsSeparatedByString:@"$"] objectAtIndex:2];DLog(@">>>>>str1:%@", dateString1);DLog(@">>>>str2:%@", dateString2); return ([dateString2 compare:dateString1]);}

To sort your array of objects you:

1. setup NSSortDescriptor - use names of your variables as keys to setup descriptor for sorting plus the selector to be executed on those keys
2. get the array of descriptors using NSSortDescriptor that you've setup
3. sort your array based on those descriptors

Here are two examples, one using NSDictionary and NSString/NSNumber values sorting onNSNumber, the other one using custom class with sorting on two NSString fields.

Follow Sorting and Filtering NSArray Objects in Cocoa programming topics to see more examples and explanation.

Example:

This was done on GNUStep it should work the same on Cocoa - the code is exactly the same - I'll try when I sit in front of my Mac:

First example usingNSString and NSNumber values with sorting on NSNumber value:

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];

---

Sorting part using descriptors with the Frequency field which is NSNumber:

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);

---

OUTPUT - sorted by Frequency field:

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; }

---

---

Second example with custom class and sorting on twoNSString variables.

Array to sort (see class A at the bottom):

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]]];

---

The sorting part, sort on lastName then firstName:

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];

---

Print the result:

NSLog(@"\nSorted ...");enumerator = [sortedArray objectEnumerator];while ((obj = [enumerator nextObject])) NSLog(@"%@", obj);

---

Result (before and after sorting):

2009-12-04 00:52:16.637 x[11375] Alehandro, Xentro, age:402009-12-04 00:52:16.644 x[11375] John, Smith, age:302009-12-04 00:52:16.644 x[11375] John, Smyth, age:252009-12-04 00:52:16.644 x[11375] Torro, Ola, age:452009-12-04 00:52:16.645 x[11375] Alehandro, Bento, age:412009-12-04 00:52:16.645 x[11375] Alehandro, Axel, age:412009-12-04 00:52:16.645 x[11375]Sorted ...2009-12-04 00:52:16.645 x[11375] Alehandro, Axel, age:412009-12-04 00:52:16.645 x[11375] Alehandro, Bento, age:412009-12-04 00:52:16.645 x[11375] Torro, Ola, age:452009-12-04 00:52:16.645 x[11375] John, Smith, age:302009-12-04 00:52:16.645 x[11375] John, Smyth, age:252009-12-04 00:52:16.645 x[11375] Alehandro, Xentro, age:40

Class A extends NSObject - nothing special here:

#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

Implementation:

#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];}

@end

 

 

http://zani.iteye.com/blog/1144910