数组排序：对象数组中根据对象的某个字段排序

1. 开发中，经常碰到数组的排序问题，当然原始的冒泡、选择排序，还是比较好用的。
2. 我们常常需要后台排好序再返回，当然也有需要前端排序的。我觉得数组的排序，根据对象数组的某个字段排序，是非常常见的。现在来说说：

---

• sortedArrayUsingSelector

 - (void)sortArray1
{
NSArray *tempArray = [NSArray arrayWithObjects:@"abc",@"123",@"bac",@"345",@"Abc", nil];
//compare:使用的是字符串自带的方法
NSArray *sortArray = [tempArray sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"%@",sortArray);
}

这种是最简单的排序。直接对数组进行排序。
- 我们看自定义compare的

//Car类 .h文件
@interface Car : NSObject
@property(nonatomic,copy)NSString *carId;
@property(nonatomic,assign)int carBuyTime;

+ (instancetype)CarWithCarId:(NSString *)carId andCarBuyTime:(int)carBuyTime;
- (NSComparisonResult)compareCar:(Car *)car;
@end
//.m 文件
#import "Car.h"

@implementation Car
+ (instancetype)CarWithCarId:(NSString *)carId andCarBuyTime:(int)carBuyTime
{
    Car *car = [[Car alloc]init];
    car.carId = carId;
    car.carBuyTime = carBuyTime;
return car;
}

- (NSComparisonResult)compareCar:(Car *)car
{
//先按照购买时间排序
   NSComparisonResult result = [[NSNumber numberWithInt:car.carBuyTime]compare:[NSNumber numberWithInt:self.carBuyTime]];
if (result == NSOrderedSame) {
      result =   [car.carId compare:car.carId];
    }
return  result;
}
@end

控制器调用：

- (void)sortArray2
{
    Car *car2 = [Car CarWithCarId:@"87323" andCarBuyTime:1988];
    Car *car3 = [Car CarWithCarId:@"87323" andCarBuyTime:1962];
    Car *car4 = [Car CarWithCarId:@"66666" andCarBuyTime:1970];
    Car *car1 = [Car CarWithCarId:@"32311" andCarBuyTime:1970];
NSArray *array = [NSArray arrayWithObjects:car1,car2,car3,car4, nil];
NSArray *sortedArray =  [array sortedArrayUsingSelector:@selector(compareCar:)];
NSLog(@"%@",sortedArray);
}

输出：

---

• sortedArrayUsingComparator

- (void)sortArray3
{
    Car *car2 = [Car CarWithCarId:@"87323" andCarBuyTime:1988];
    Car *car3 = [Car CarWithCarId:@"87323" andCarBuyTime:1962];
    Car *car4 = [Car CarWithCarId:@"66666" andCarBuyTime:1970];
    Car *car1 = [Car CarWithCarId:@"32311" andCarBuyTime:1970];
    NSArray *array = [NSArray arrayWithObjects:car1,car2,car3,car4, nil];

  array =   [array sortedArrayUsingComparator:^NSComparisonResult(Car * obj1, Car * obj2) {
      NSComparisonResult result = [[NSNumber numberWithInt:obj1.carBuyTime]compare:[NSNumber numberWithInt:obj2.carBuyTime]];
if (result == NSOrderedSame) {
          result =   [obj1.carId compare:obj2.carId];
      }
return  result;
    }];

}