OC数组排序

 1.使用NSSortDescriptor对象进行数组排序

//创建一个数组

NSArray *array = @[@"one", @"two", @"three", @"four", @"six"];

//创建一个排序条件，也就是一个NSSortDescriptor对象

//其中第一个参数为数组中对象要按照什么属性来排序(比如自身、姓名，年龄等)

//第二个参数为指定排序方式是升序还是降序

//ascending  排序的意思，默认为YES 升序

NSSortDescriptor *des = [[NSSortDescriptor alloc] initWithKey:@"self" ascending:YES];

NSArray *newArray = [array sortedArrayUsingDescriptors:@[des]];

NSLog(@"%@",newArray);

2.使用sortedArrayUsingDescriptors:方法实现把多个排序条件放到数组中，实现多条件排序，按数组先后顺序，先加入的优先级高

//创建一个Person类

Person *p1 = [[Person alloc] initWithName:@"zhonger" age:@"19"];

Person *p2 = [[Person alloc] initWithName:@"zhubada" age:@"11"];

Person *p3 = [[Person alloc] initWithName:@"zhubada" age:@"1"];

Person *p4 = [[Person alloc] initWithName:@"zhubada" age:@"33"];

Person *p5 = [[Person alloc] initWithName:@"hehehe" age:@"38"];

NSArray *person = @[p1, p2, p3, p4, p5];

NSSortDescriptor *des1 = [[NSSortDescriptor alloc]initWithKey:@"name" ascending:YES];

NSSortDescriptor *des2 = [[NSSortDescriptor alloc] initWithKey:@"age" ascending:NO];

NSArray *newArray1 = [person sortedArrayUsingDescriptors:@[des1,des2]];

NSLog(@"%@",newArray1);

3.使用sortedArrayUsingComparator进行数组排序

Comparator的返回结构枚举类型含义：

NSOrderedAscending//升序

The left operand is smaller than the right operand.

NSOrderedSame

The two operands are equal.

NSOrderedDescending//降序

The left operand is greater than the right operand.

直接使用代码块对字典里具体属性进行排序

NSString *arr = [arr sortedArrayUsingComparator:^NSComparisonResult(id _Nonnull obj1, id _Nonnull obj2) {

NSString *age1 = [obj1 objectForKey:@"age"];

NSString *age2 = [obj2 objectForKey:@"age"];

//转换成NSNumber便于直接使用compare：方法直接排序

NSNumber *num1 = [NSNumber numberWithInteger:age1];

NSNumber *num2 = [NSNumber numberWithInteger:age2];

//升序

NSComparisonResult result = [num1 compare:num2];

return result;

}];

NSLog(@"%@",arr);

//其中compare：内部实现类似于下(也可自定义对象的比较方法)

NSComparator cmp = ^(id obj1, id obj2) {

if ([obj1 integerValue] < [obj2 integerValue]) {

      return (NSComparisonResult)NSOrderedAscending;        

}else if ([obj1 integerValue] > [obj2 integerValue]) {

      return (NSComparisonResult)NSOrderedDescending; 

}else {

      return (NSComparisonResult)NSOrderedSame;

};