[英]How to sort an NSMutableArray
my class like this: 我的班级是这样的:
car
--------------
price
color
I created an NSMutableArray that contains several of these car objects, how to sort the NSMutableArray by price 我创建了一个NSMutableArray,其中包含几个这样的汽车对象,如何按价格对NSMutableArray进行排序
Using a comparator it may look like this: 使用比较器可能如下所示:
NSMutableArray *cars= [NSMutableArray arrayWithCapacity:5];
[cars addObject:[[[Car alloc] initWithColor:@"blue" price:30000.0] autorelease]];
[cars addObject:[[[Car alloc] initWithColor:@"yellow" price:35000.0] autorelease]];
[cars addObject:[[[Car alloc] initWithColor:@"black" price:29000.0] autorelease]];
[cars addObject:[[[Car alloc] initWithColor:@"green" price:42000.0] autorelease]];
[cars addObject:[[[Car alloc] initWithColor:@"white" price:5000.0] autorelease]];
[cars sortUsingComparator:^NSComparisonResult(Car *car1, Car *car2) {
if (car1.price < car2.price)
return (NSComparisonResult)NSOrderedAscending;
if (car1.price > car2.price)
return (NSComparisonResult)NSOrderedDescending;
return (NSComparisonResult)NSOrderedSame;
}];
NSLog(@"%@", cars);
And this is my Car class: 这是我的Car类:
@interface Car : NSObject
@property (nonatomic, copy)NSString *colorName;
@property (nonatomic) float price;
-(id)initWithColor:(NSString *)colorName price:(float)price;
@end
@implementation Car
@synthesize colorName = colorName_;
@synthesize price = price_;
-(id)initWithColor:(NSString *)colorName price:(float)price
{
if (self = [super init]) {
colorName_ = [colorName copy];
price_ = price;
}
return self;
}
- (void)dealloc {
[colorName_ release];
[super dealloc];
}
-(NSString *)description
{
return [NSString stringWithFormat:@"%@ %f", self.colorName, self.price];
}
@end
Sorting an array has built-in junk you should use due to fast enumeration. 排序数组有内置垃圾,你应该使用快速枚举。 For Dictionary keys, I use a bubble sort like this: 对于字典键,我使用这样的冒泡排序:
- (NSMutableArray*) bubbleSortDictKeys:(NSDictionary*)dict {
if(!dict)
return nil;
NSMutableArray *sortedKeys = [NSMutableArray arrayWithArray: [dict allKeys]];
if([sortedKeys count] <= 0)
return nil;
else if([sortedKeys count] == 1)
return sortedKeys;
int n = [sortedKeys count] -1, i;
BOOL swapped = YES;
NSString *key1,*key2;
NSComparisonResult result;
while(swapped)
{
swapped = NO;
for( i = 0; i < n; i++ )
{
key1 = [sortedKeys objectAtIndex: i];
key2 = [sortedKeys objectAtIndex: i + 1];
result = [key1 compare: key2 options: NSCaseInsensitiveSearch];
if(result == NSOrderedDescending)
{
[key1 retain]; [key2 retain];
[sortedKeys exchangeObjectAtIndex:i withObjectAtIndex:i+1];
[key1 release]; [key2 release];
swapped = YES;
}
}
}
return sortedKeys;
}
Then you can use this function like so: 然后您可以像这样使用此功能:
NSEnumerator *keys = [[self bubbleSortDictKeys:dict] objectEnumerator];
For your reference here is a list of built-in array sorting methods: 这里有一个内置数组排序方法列表供您参考:
For completeness in response to my comment below here is how you would use a sort descriptory on a dictionary of keys or any array: 为了完整性以回应我在下面的评论,这里是如何在键或任何数组的字典上使用排序描述:
NSArray *arrayToSort, *sortedArray;
arrayToSort = [NSArray arrayWithObjects:car1, car2, car3, nil];
NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:@"color" ascending:YES];
sortedArray = [arrayToSort sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]];
// Use your sortedArray
Enjoy. 请享用。
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