iOS笔记之数组排序-白红宇

简单说明

数组排序比较多，我们讲一种比较常用的，这里涉及到一个知识点： NSComparisonResult：

typedef enum NSComparisonResult : NSInteger {    NSOrderedAscending = -1L,    NSOrderedSame,    NSOrderedDescending} NSComparisonResult;复制代码

NSOrderedAscending： 左边数据比右边小，可理解成增序

NSOrderedSame： 相等

NSOrderedDescending： 左边数据比右边大，可理解成降序

示例：

NSArray *array = @[@"Benz",@"BMW",@"Ferrari",@"Lamborghini"];复制代码

1、普通排序系统自带的升序

NSArray *sortedArray1 = [array sortedArrayUsingSelector:@selector(compare:)];NSLog(@"普通排序:%@",sortedArray1);复制代码

2、逆转数组

NSArray *sortedArray2 = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1,id obj2) {  //逆转  return NSOrderedDescending;}];NSLog(@"逆转数组:%@",sortedArray2);复制代码

3、不逆转（相当于原数组）

NSArray *sortedArray3 = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1,id obj2) {  //不逆转  return NSOrderedAscending;}];NSLog(@"不逆转(原数据):%@",sortedArray3);复制代码

4、升序排列

NSArray *sortedArray4 = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1,id obj2) {  //升序  NSComparisonResult result = [obj1 compare: obj2];  return result;}];NSLog(@"升序排列:%@",sortedArray4);复制代码

5、降序排列

NSArray *sortedArray5 = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {  //降序  NSComparisonResult result = [obj1  compare: obj2];  return -result;}];NSLog(@"降序排列:%@",sortedArray5);复制代码

进阶：

数组里面存放模型，根据模型的某个属性值来对数组进行重新排序

1)、初始化一些车辆和数组：

Car *benz = [Car new];benz.name = @"Benz";benz.price = 2000.0;    Car *bmw = [Car new];bmw.name = @"BMW";bmw.price = 800;    Car *ferrari = [Car new];ferrari.name = @"Ferrari";ferrari.price = 1200;    Car *lamborghini = [Car new];lamborghini.name = @"Lamborghini";lamborghini.price = 12000;    NSMutableArray *array = @[benz,bmw,ferrari,lamborghini].mutableCopy;复制代码

2)、排序方法

/** 对数组里存放model的某个属性对数组进行重新排序 @param array 待排序数组 @param increase 是否增序排列 @param key 属性 @return <#return value description#> */-(NSArray *)sortArray:(NSArray *)array increase:(BOOL)increase byKey:(NSString *)key{        array = [array sortedArrayUsingComparator:             ^NSComparisonResult(Car *obj1, Car *obj2) {                 NSComparisonResult result;                 if ([key isEqualToString:@"price"]) {                     CGFloat res1 = [[obj1 valueForKey:key] floatValue];                     CGFloat res2 = [[obj2 valueForKey:key] floatValue];                     if (increase) {                         if (res1 < res2){                             result = NSOrderedAscending;                         }else {                             result = NSOrderedDescending;                         }                     } else {                         if (res1 < res2){                             result = NSOrderedDescending;                         }else {                             result = NSOrderedAscending;                         }                     }                 } else {                     result = [[obj1 valueForKey:key] compare:[obj2 valueForKey:key]];                     if (!increase) {                         if (result == NSOrderedDescending) {                             result = NSOrderedAscending;                         } else if (result == NSOrderedAscending) {                             result = NSOrderedDescending;                         }                     }                 }                                  return result;             }].mutableCopy;    return array;}复制代码

3)、打印结果

NSArray *sortArray;sortArray = [self sortArray:array increase:YES byKey:@"price"];NSLog(@"increase by price:");for (Car *c in sortArray) {  NSLog(@"car:%@ -->price:%lf\n",c.name,c.price);}NSLog(@"------分割线------");sortArray = [self sortArray:array increase:NO byKey:@"price"];NSLog(@"descend by price:");for (Car *c in sortArray) {  NSLog(@"car:%@ -->price:%lf\n",c.name,c.price);}NSLog(@"------分割线------");    sortArray = [self sortArray:array increase:YES byKey:@"name"];NSLog(@"increase by name:");for (Car *c in sortArray) {  NSLog(@"car:%@ -->price:%lf\n",c.name,c.price);}NSLog(@"------分割线------");    sortArray = [self sortArray:array increase:NO byKey:@"name"];NSLog(@"descend by name:");for (Car *c in sortArray) {  NSLog(@"car:%@ -->price:%lf\n",c.name,c.price);}复制代码

Warnning: 可能有眼尖的看客发现了，increase by name和descend by name顺序不对，升序的时候Benz不应该在BMW前面吗？降序Benz在BMW后面吗？注意，这里M是大写，而e是小写，大写的ASCII码在小写前面，所以M比e前。

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