NSArray排序方法

从网上查的，非常方便的排序api，功能也很强大

1.sortedArrayUsingSelector

（按Key值大小对NSDictionary排序）

NSMutableArray *array = [NSMutableArray arrayWithObjects:                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj0", [NSNumber numberWithInt:0], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj5", [NSNumber numberWithInt:5], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj2", [NSNumber numberWithInt:2], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj3", [NSNumber numberWithInt:3], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj1", [NSNumber numberWithInt:1], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj4", [NSNumber numberWithInt:4], nil], nil];    NSArray *resultArray = [array sortedArrayUsingSelector:@selector(compare:)];

因为NSDictionary没有compare的排序比较方法，所以需要我们自己写一个

- (NSComparisonResult)compare: (NSDictionary *)otherDictionary{    NSDictionary *tempDictionary = (NSDictionary *)self;        NSNumber *number1 = [[tempDictionary allKeys] objectAtIndex:0];    NSNumber *number2 = [[otherDictionary allKeys] objectAtIndex:0];        NSComparisonResult result = [number1 compare:number2];        return result == NSOrderedDescending; // 升序//    return result == NSOrderedAscending;  // 降序}

2.sortedArrayUsingComparator

    NSMutableArray *array = [NSMutableArray arrayWithObjects:                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj0", [NSNumber numberWithInt:0], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj5", [NSNumber numberWithInt:5], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj2", [NSNumber numberWithInt:2], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj3", [NSNumber numberWithInt:3], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj1", [NSNumber numberWithInt:1], nil],                             [NSDictionary dictionaryWithObjectsAndKeys:@"Obj4", [NSNumber numberWithInt:4], nil], nil];    //    NSArray *resultArray = [array sortedArrayUsingSelector:@selector(compare:)];        NSArray *resultArray = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {                NSNumber *number1 = [[obj1 allKeys] objectAtIndex:0];        NSNumber *number2 = [[obj2 allKeys] objectAtIndex:0];                NSComparisonResult result = [number1 compare:number2];                return result == NSOrderedDescending; // 升序//        return result == NSOrderedAscending;  // 降序    }];

3.sortedArrayUsingDescriptors & sortUsingDescriptors

前者带返回值，是NSArray的方法，排好序的数组是返回值中的数组；

后者不带返回值，是NSMutableArray的方法，是对当前数组自己排序

接下来根据一个对象的属性，排列这个对象

.h@interface Person : NSObject{    NSString  *_name;        NSInteger  _age;}@property (nonatomic, retain) NSString  *name;@property (nonatomic, assign) NSInteger  age;@end.m@implementation Person@synthesize name = _name;@synthesize age  = _age;- (void)dealloc{    [_name release];        [super dealloc];}@end

排序方法的实现

    Person *person1 = [[Person alloc] init];    [person1 setName:@"ABC"];    [person1 setAge:24];        Person *person2 = [[Person alloc] init];    [person2 setName:@"ACB"];    [person2 setAge:22];        Person *person3 = [[Person alloc] init];    [person3 setName:@"ABD"];    [person3 setAge:33];        NSMutableArray *array = [NSMutableArray arrayWithObjects:person1, person2, person3, nil];    [person1 release];    [person2 release];    [person3 release];    //这里类似KVO的读取属性的方法，直接从字符串读取对象属性，注意不要写错    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"_age" ascending:YES];    //这个数组保存的是排序好的对象    NSArray *tempArray = [array sortedArrayUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];        for(NSInteger i = 0; i < [tempArray count]; i++)    {        NSLog(@"%@--------%d\n", [[tempArray objectAtIndex:i] name], [[tempArray objectAtIndex:i] age]);    }//下面是可变数组的方法   //    [array sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];//    //    for(NSInteger i = 0; i < [array count]; i++)//    {//        NSLog(@"%@--------%d\n", [[array objectAtIndex:i] name], [[array objectAtIndex:i] age]);//    }

   NSSortDescriptor *sortDescriptor1 = [NSSortDescriptorsortDescriptorWithKey:@"_age"ascending:YES];

   NSSortDescriptor *sortDescriptor2 = [NSSortDescriptorsortDescriptorWithKey:@"_name"ascending:YES];

   NSArray *tempArray = [array sortedArrayUsingDescriptors:[NSArrayarrayWithObjects:sortDescriptor1, sortDescriptor2, nil]];

   这里的NSArray中的第一元素表示首先按照这个元素的升序或者降序进行排序,对于有重复项的，再按照第二元素进行排序，依次进行类推