我的OC成长之路（复习）

一、数组

1.简单的数组排序(sortedArrayUsingSelector:)

NSArray *array = @[@123,@7889,@231];
NSArray *sortArray =[array sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"%@",sortArray);

　　//字符串对比，会根据逐个字符进行对比排序

NSComparisonResult compare(id obj1,id obj2){
    if (obj1 < obj2) {
        return NSOrderedAscending;//升序
    }
    if (obj1 > obj2) {
        return NSOrderedDescending;//降序
    }else return NSOrderedSame;//相同
}

2.使用block语法(sortedArrayUsingCompartor)

NSArray *sortArray2 = [array sortedArrayUsingComparator: ^NSComparisonResult(id _Nonnull obj1,id _Nonnull obj2){
            if (obj1 < obj2) {
                return NSOrderedAscending;//升序
            }
            if (obj1 > obj2) {
                return NSOrderedDescending;//降序
            }else return NSOrderedSame;//相同
        }];

3.高级排序（sortedArrayUsingDescriptors:）

　　main

Person *p1 = [[Person alloc] init];
p1.name = @"Jack";
p1.age = 17;
Person *p2 = [[Person alloc]initWithName:@"Mary" andAge:19];
Person *p3 = [[Person alloc]initWithName:@"Hop" andAge:22];
NSArray *obj = [NSArray arrayWithObjects:p1,p2,p3,nil];
//创建排序描述器
NSSortDescriptor *nameDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];
NSSortDescriptor *ageDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];

//将描述器再装起来
NSArray < NSSortDescriptor *>*descriptorArray =[NSArray arrayWithObjects:nameDescriptor ,ageDescriptor,nil];
NSArray *sortArray3 = [obj sortedArrayUsingDescriptors:descriptorArray];
NSLog(@"%@",sortArray3);

　　.h

#import <Foundation/Foundation.h>

@interface Person : NSObject

@property (nonatomic,copy) NSString *name;
@property (nonatomic,assign) int age;

- (id)initWithName:(NSString *)name andAge:(int)age;
- (NSString *)description;

@end

　　.m

#import "Person.h"

@implementation Person

- (id)initWithName:(NSString *)name andAge:(int)age{

    if (self = [super init]) {
        _name = name;
        _age = age;
    }
    return self;
}

- (NSString *)description{
    return [NSString stringWithFormat:@"name = %@ age = %d",_name,_age];
}

@end

二、字典

1.第一种排序方法

NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@23232,@"A",@7878,@"B", nil];
[dict keysSortedByValueUsingSelector:@selector(compare:)];
 NSLog(@"%@",dict);

2.第二种排序方法

[dict keysSortedByValueUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
　　if (obj1 < obj2) {
   　　return NSOrderedAscending;//升序
   }
   if (obj1 > obj2) {
   　　return NSOrderedDescending;//降序
   }else return NSOrderedSame;//相同}];
NSLog(@"%@",dict);