如何对自定义NSArray排序？

Question

我有一个班级办公室

@interface OfficeSupply : NSObject

@property (nonatomic, strong) NSString *itemName;
@property (nonatomic) int total;
@property (nonatomic) int price;
@property (nonatomic) int quantity;
@property (nonatomic, strong) UITextField *quantityText;
@property (nonatomic, strong) UIImage *itemPic;

-(id)initWithName:(NSString *)itemName total:(int)total price:(int)price quantity:(int)quantity picture:(UIImage *)itemPic;

@end

在我看来，我有

 OfficeSupply *item1 = [[OfficeSupply alloc] initWithName:@"Stapler" total:0 price:50 quantity:0 picture:[UIImage imageNamed:@"stapler.jpg"]];
OfficeSupply *item2 = [[OfficeSupply alloc] initWithName:@"Paper" total:0 price:150 quantity:0 picture:[UIImage imageNamed:@"101291.jpg"]];
OfficeSupply *item3 = [[OfficeSupply alloc] initWithName:@"Pen" total:0 price:45 quantity:0 picture:[UIImage imageNamed:@"pen.jpg"]];
_items =[NSArray arrayWithObjects:item1, item2, item3, nil];

[_items sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

我已经查找了问题，但无法解决我的问题。

最后一行应该对它进行排序，但我不知道为什么不会。

我只想按名称排序。有什么想法吗？

Answer 1

您无法编辑NSArray因为它是不可变的，因此您需要执行以下操作：

_items = [_items sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

Answer 2

调用sortedArrayUsingDescriptors:返回一个NSArray实例，该实例是您在其上调用该方法的实例的排序表示形式。 所以：

NSArray *sortedItems = [_items sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

您还可以通过对排序描述符数组使用文字语法来进一步简化操作。

NSArray *sortedItems = [_items sortedArrayUsingDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

如果要继续更改_items NSArray实例，则create是作为NSMutableArray开头的。

// Make sure _items instance variable is declared as an NSMutableArray    
_items =[NSMutableArray arrayWithObjects:item1, item2, item3, nil];

[_items sortUsingDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

Answer 3

将_items作为NSMutableArray ...

NSArray *sortedArray;
sortedArray=[_items sortedArrayUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"itemName" ascending:YES selector:@selector(caseInsensitiveCompare:)]]];

[_items removeAllObjects];
[_items addObjectsFromArray:sortedArray];