NSMutable sort排序

最新推荐文章于 2022-03-20 10:41:25 发布

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最新推荐文章于 2022-03-20 10:41:25 发布

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文章标签：操作系统

原文链接：http://www.cnblogs.com/likwo/p/3983664.html

本文详细介绍了如何在Objective-C和Swift中为对象实现自定义比较方法，进而实现对象数组的排序。通过使用比较方法、NSSortDescriptor和块（block），可以轻松地按照一个或多个属性对对象数组进行排序。文章还提供了实例代码和说明，帮助开发者快速掌握排序技巧。

Compare method

Either you implement a compare-method for your object:

- (NSComparisonResult)compare:(Person *)otherObject {
    return [self.birthDate compare:otherObject.birthDate];
}

NSArray *sortedArray;
sortedArray = [drinkDetails sortedArrayUsingSelector:@selector(compare:)];

NSSortDescriptor (better)

or usually even better:

NSSortDescriptor *sortDescriptor;
sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:@"birthDate"
                                              ascending:YES] autorelease];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
NSArray *sortedArray;
sortedArray = [drinkDetails sortedArrayUsingDescriptors:sortDescriptors];

You can easily sort by multiple keys by adding more than one to the array. Using custom comparator-methods is possible as well. Have a look at the documentation.

Blocks (shiny!)

There's also the possibility of sorting with a block since Mac OS X 10.6 and iOS 4:

NSArray *sortedArray;
sortedArray = [drinkDetails sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
    NSDate *first = [(Person*)a birthDate];
    NSDate *second = [(Person*)b birthDate];
    return [first compare:second];
}];

For this particular example I'm assuming that the objects in your array have a 'position' method, which returns an NSInteger.

NSArray *arrayToSort = where ever you get the array from... ;
NSComparisonResult (^sortBlock)(id, id) = ^(id obj1, id obj2) {
  if ([obj1 position] > [obj2 position]) { 
    return (NSComparisonResult)NSOrderedDescending;
  }
  if ([obj1 position] < [obj2 position]) {
    return (NSComparisonResult)NSOrderedAscending;
  }
  return (NSComparisonResult)NSOrderedSame;
};
NSArray *sorted = [arrayToSort sortedArrayUsingComparator:sortBlock];

Note: the "sorted" array will be autoreleased.