数组的排序及筛选

sortedArrayUsingComparator

NSArray *array = @[@"4",@"2",@"3",@"1",@"3"];

NSLog(@"排序前: %@",array);

NSComparator comparator = ^(id obj1, id obj2){
    if([obj1 integerValue] > [obj2 integerValue])
    {
        return NSOrderedDescending;
    }
    if([obj1 integerValue] < [obj2 integerValue])
    {
        return NSOrderedAscending;
    }
    return NSOrderedSame;

    //return (arc4random() % 3) - 1; //随机排序
};

array = [array sortedArrayUsingComparator:comparator];

NSLog(@"排序后: %@",array);

sortedArrayUsingComparator

sortedArrayUsingFunction:customSort

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSArray *array = @[@"4",@"2",@"3",@"1",@"3"];

    NSLog(@"排序前: %@",array);

    array = [array sortedArrayUsingFunction:customSort context:nil];

    NSLog(@"排序后: %@",array);
}

NSInteger customSort(id obj1, id obj2, void* context)
{
     if ([obj1 integerValue] > [obj2 integerValue])
     {
         return NSOrderedDescending;
     }

     if ([obj1 integerValue] < [obj2 integerValue])
     {
         return NSOrderedAscending;
     }
     return NSOrderedSame;
}

sortedArrayUsingFunction:customSort

sortUsingDescriptors

#import <Foundation/Foundation.h>

@interface TopMenuItem : NSObject

@property (strong, nonatomic) NSString *title;
@property (assign, nonatomic) NSInteger order;
@property (assign, nonatomic) BOOL selected;

@end

#import "TopMenuItem.h"

@implementation TopMenuItem

- (NSString *)description
{
    return [NSString stringWithFormat:@"title:%@, order:%d, selected:%d",self.title,self.order,self.selected];
}

@end

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSMutableArray *channelArray = [NSMutableArray array];

    TopMenuItem *item = [[TopMenuItem alloc] init];
    item.title = @"要闻";
    item.order = 1;
    item.selected = YES;
    [channelArray addObject:item];

    item = [[TopMenuItem alloc] init];
    item.title = @"半导体照明";
    item.selected = YES;
    item.order = 3;
    [channelArray addObject:item];

    item = [[TopMenuItem alloc] init];
    item.title = @"电子工程";
    item.selected = YES;
    item.order = 2;
    [channelArray addObject:item];

    item = [[TopMenuItem alloc] init];
    item.title = @"光通讯";
    item.selected = NO;
    item.order = 3;
    [channelArray addObject:item];

    NSLog(@"排序前");
    for (TopMenuItem *item in channelArray)
    {
        NSLog(@"%@",item);
    }

    NSSortDescriptor *sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"order" ascending:YES];
    NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"selected" ascending:YES];

    [channelArray sortUsingDescriptors:[NSArray arrayWithObjects:sortDescriptor1, sortDescriptor2, nil]];

    NSLog(@"排序后");
    for (TopMenuItem *item in channelArray)
    {
        NSLog(@"%@",item);
    }
}

sortUsingDescriptors

makeObjectsPerformSelector

这个方法可以让数组内的所有元素都执行同一个对象方法，在特定场合可以替代for循环使用。

还是沿用上面例子里的TopMenuItem类，新加入一个方法：

- (void)testFun:(NSString *)str
{
    NSLog(@"testFun,param is:%@,title is %@",str,self.title);
}

然后就可以这样调用：

[channelArray makeObjectsPerformSelector:@selector(testFun:) withObject:@"测试"];

NSPredicate

Cocoa框架中的NSPredicate主要用于查询并过滤元素，比较类似于Sql语句中的where，使用方法如下：

NSArray *array = @[@"A",@"AB",@"ABC",@"D",@"DF"];

NSLog(@"排序前: %@",array);

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF Contains ‘A‘"];
NSArray *newArray = [array filteredArrayUsingPredicate:predicate];

NSLog(@"排序后: %@",newArray);

如果是NSMutableArray，则可以直接调用filterUsingPredicate来过滤原数组。

比较运算符

>  >=  <  <=  ==  !=(或<>)

NSMutableArray *array = [NSMutableArray arrayWithArray:@[[NSNumber numberWithInt:1],
                                                         [NSNumber numberWithInt:4],
                                                         [NSNumber numberWithInt:23],
                                                         [NSNumber numberWithInt:999],
                                                         [NSNumber numberWithInt:83],]];

NSLog(@"原数组: %@",array);

NSString *filterString = @"SELF>50"; //get 83,999
filterString = @"SELF==23"; //get 23
filterString = @"SELF<=23"; //get 1,4,23

NSPredicate *predicate = [NSPredicate predicateWithFormat:filterString];

[array filterUsingPredicate:predicate];

NSLog(@"过滤后: %@",array);

Code

范围运算符

IN  BETWEEN

NSMutableArray *array = [NSMutableArray arrayWithArray:@[[NSNumber numberWithInt:1],
                                                         [NSNumber numberWithInt:4],
                                                         [NSNumber numberWithInt:23],
                                                         [NSNumber numberWithInt:999],
                                                         [NSNumber numberWithInt:83],]];

NSLog(@"原数组: %@",array);

NSString *filterString = @"SELF BETWEEN {4,50}"; //get 4,23
filterString = @"SELF IN {23,999}"; //get 23,999

NSPredicate *predicate = [NSPredicate predicateWithFormat:filterString];

[array filterUsingPredicate:predicate];

NSLog(@"过滤后: %@",array);

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字符串比较

LIKE  BEGINWITH  CONTAINS  ENDSWITH  MATCHES

NSArray *array = @[@"park",@"army",@"phone",@"warrior",@"stone",@"ear",@"apple",@"application",@"wear"];

NSString *filterString = @"SELF LIKE[cd] ‘*ar‘"; //get "ear","wear"

filterString = @"SELF LIKE[cd] ‘?ar‘"; //get "ear"

filterString = @"SELF LIKE[cd] ‘?ar?‘"; //get "park"

filterString = @"SELF LIKE[cd] ‘?ar*‘ && SELF ENDSWITH[cd] ‘r‘"; //get "warrior","ear"

filterString = @"SELF BEGINSWITH[cd] ‘e‘ || SELF BEGINSWITH[cd] ‘s‘"; //get "stone","ear"(匹配以"e"或"s"开头的单词)

filterString = @"SELF BEGINSWITH[cd] ‘app‘"; //get "apple","application"

filterString = @"SELF ENDSWITH[cd] ‘one‘"; //get "stone","phone"

filterString = @"SELF MATCHES[cd] ‘^w.+r$‘"; //get "warrior","wear"(正则匹配以"w"开头，"r"结尾的单词)

NSPredicate *predicate = [NSPredicate predicateWithFormat:filterString];

NSLog(@"过滤结果: %@",[array filteredArrayUsingPredicate:predicate]);

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上面的例子都是直接利用SELF比较，如果数组存储的是对象，要以对象的属性值作为筛选目标可以这样：

NSMutableArray *channelArray = [NSMutableArray array];

TopMenuItem *item = [[TopMenuItem alloc] init];
item.title = @"要闻";
item.order = 1;
item.selected = YES;
[channelArray addObject:item];

item = [[TopMenuItem alloc] init];
item.title = @"半导体照明";
item.selected = NO;
item.order = 5;
[channelArray addObject:item];

item = [[TopMenuItem alloc] init];
item.title = @"电子工程";
item.selected = YES;
item.order = 2;
[channelArray addObject:item];

item = [[TopMenuItem alloc] init];
item.title = @"光通讯";
item.selected = NO;
item.order = 3;
[channelArray addObject:item];

item = [[TopMenuItem alloc] init];
item.title = @"太阳能光伏";
item.selected = YES;
item.order = 4;
[channelArray addObject:item];

NSString *filterString = @"title CONTAINS[cd] ‘光‘";

filterString = @"selected==1";

filterString = @"order BETWEEN {3,5}";

NSPredicate *predicate = [NSPredicate predicateWithFormat:filterString];

NSArray *filteredArray = [channelArray filteredArrayUsingPredicate:predicate];

for (TopMenuItem *item in filteredArray)
{
    NSLog(@"%@",item);
}

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