在NSArray中排序对象？

Question

I have an object, as below

#import <Foundation/Foundation.h>

@interface CountriesDAO : NSObject

@property (nonatomic, retain) NSString * countryname;

@end



#import "CountriesDAO.h"

@implementation CountriesDAO
@synthesize countryname;

@end

I have saved this in Array within appDelegate.

@property (nonatomic, retain) NSArray *countriesArray;

@synthesize countriesArray;

In another controller, I fetch it like

  NSArray *countriesArray = appDelegate.countriesArray; It works fine and I get array.

As I try to sort it by this way.

 NSArray *countriesArray1 = appDelegate.countriesArray;
    NSSortDescriptor *valueDescriptor = [[NSSortDescriptor alloc] initWithKey:@"countryname" ascending:YES];
    NSArray * descriptors = [NSArray arrayWithObject:valueDescriptor];

    countriesArray = [countriesArray1 sortedArrayUsingDescriptors:descriptors];

I get error

[__NSCFType count]: unrecognized selector sent to instance 0xa83b4d0
2013-11-01 13:21:08.882 ECP[13597:c07] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFType count]: unrecognized selector sent to instance 0xa83b4d0'

Here countriesArray is defined as

 @property (nonatomic, retain) NSArray *countriesArray;

Answer 1

您也可以尝试...

[countriesArray1 sortUsingSelector:@selector(compare:)];

Answer 2

I did it like this and it worked for me.

countriesArray = [[NSMutableArray alloc] init];


for (CountriesDAO *info in appDelegate.countriesArray) {
    [countriesArray addObject:info.countryname];
}    

[countriesArray sortUsingSelector:@selector(localizedCaseInsensitiveCompare:)];

Answer 3

Should work

NSMutableArray *sortedArray = [appDelegate.countriesArray mutableCopy];
[sortedArray sortUsingComparator:^NSComparisonResult(CountriesDAO *object1, 
                                                     CountriesDAO *object2) {                
    return [object1.countryname caseInsensitiveCompare:object2.countryname];
}];
NSArray *sortedCountriesArray = [sortedArray copy];

If something went wrong, check the type of object1 and object2

Answer 4

Its is simple Way to sort array in iOS,it's helps to you

[countriesArray sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        return [ String_1 compare: String_2];
    }];

// String_1, String_2 are NSString,it's contains in countriesArray
// use  NSMutableArray to rearrange and change values in countriesArray

Answer 5

如果要排序的数组包含NSString（这是我从您的描述中得到的），则可以使用以下代码替换排序代码：

sortedArray = [countriesArray1 sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];