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无序的去重
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1.利用NSDictionary的AllKeys（AllValues）方法
可以将NSArray中的元素存入一个字典，然后利用AllKeys或者AllValues取得字典的所有键或值，这些键或值都是去重的
NSArray *originalArray = @[@1, @2, @3, @1, @3]; NSMutableDictionary *dict = [NSMutableDictionary dictionary]; for (NSNumber *n in originalArray) { [dict setObject:n forKey:n]; } NSLog(@"dict: %@",[dict allValues]);
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2.利用NSSet特性, 放入集合自动去重
NSSet的特性: 确定性、无序性、互异性
NSArray *originalArray = @[@1, @2, @3, @1, @3]; NSSet *set = [NSSet setWithArray:originalArray]; NSLog(@"result: %@", [set allObjects]);
注：如果需要排序，可以使用NSSortDescriptor类（参考iOS - 排序: NSSortDescriptor）
有序的去重
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1.开辟新的内存空间(使用containsObject：方法)
判断是否存在，若不存在则添加到数组中，得到最终结果的顺序不发生变化
NSArray *originalArray = @[@1, @2, @3, @1, @3]; NSMutableArray *resultArray = [NSMutableArray array]; for (NSString *item in originalArray) { if (![resultArray containsObject:item]) { [resultArray addObject:item]; } } NSLog(@"resultArray : %@", resultArray); -
2.通过valueForKeyPath (@"@distinctUnionOfObjects.self")
NSArray *originalArray = @[@1, @2, @3, @1, @3]; NSArray *resultArray = [originalArray valueForKeyPath:@"@distinctUnionOfObjects.self"]; NSLog(@"result: %@", resultArray);
模型对象的去重
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1.通过model类的唯一标识来判断
- 定义一个简单的model类
// Model.h @interface Model : NSObject @property (nonatomic, copy) NSString *ID; @property (nonatomic, copy) NSString *name; @end // Model.m @implementation Model @end- 去除数组中重复model对象
//创建model类对象 Model *model1 = [[Model alloc]init]; model1.ID = @"1"; Model *model2 = [[Model alloc]init]; model1.ID = @"2"; Model *model3 = [[Model alloc]init]; model1.ID = @"3"; Model *model4 = [[Model alloc]init]; model1.ID = @"1"; Model *model5 = [[Model alloc]init]; model1.ID = @"3"; //添加到数组中 NSMutableArray *originalArray = [NSMutableArray arrayWithArray:@[model1,model2,model3,model4,model5]]; NSMutableArray *resultArray = [NSMutableArray arrayWithArray:originalArray]; //去重 for (NSInteger x = 0; x < originalArray.count; x++) { for (NSInteger y = x+1;y < originalArray.count; y++) { Model *tempModel = originalArray[x]; Model *model = originalArray[y]; if ([tempModel.ID isEqualToString:model.ID]) { [resultArray removeObject:model]; } } } NSLog(@"result: %@", resultArray);
