nspredicate

问题 How to write NSPredicate to fetch the rows that matches with values in the array? E.g: [NSPredicate predicateWithFormat:@"UserName IN %@",UserIDArray]; If UserIDArray contains ID of users, how does one fetch the user name which matches with the values in this array? 回答1: Let me start with this advice. Core Data is not SQL. Entities are not tables. Objects are not rows. Columns are not attributes/properties. Core Data is an object graph management system that may or may not persist the object

问题 I was wondering if there is a way to simplify an NSPredicate that takes in a single query string for multiple comparison targets. I'm searching multiple attributes of a core data entity for the same query string. My current query looks something like this... [NSPredicate predicateWithFormat:@"(attributeA contains[cd] %@) OR (attributeB contains[cd] %@) OR (attributeC contains[cd] %@)", searchString, searchString, searchString]; Note that this works perfectly, but it does look a bit unsightly.

问题 I need to filter an NSMutableArray of custom objects and was wondering about whether or not one of the following is BETTER than the other in terms of speed/runtime, or if they are virtually the same: (1) Using [array filterUsingPredicate:predicate], or (2) Using a for loop to iterate through all elements and check if they satisfy the criteria or not myself. I only ask this because I think the criteria each object must satisfy could vary so making the predicate could be tricky. Thanks in

问题 I've got the following setup: @interface Item : NSObject { NSInteger *item_id; NSString *title; UIImage *item_icon; } @property (nonatomic, copy) NSString *title; @property (nonatomic, assign) NSInteger *item_id; @property (nonatomic, strong) UIImage *item_icon; - (NSString *)path; - (id)initWithDictionary:(NSDictionary *)dictionairy; @end And #import <Foundation/Foundation.h> #import "Item.h" @interface Category : Item { } - (NSString *)path; @end I've got an array with Category instances

问题 I have an NSPredication with format like this: @"Status CONTAINS[cd] shipped" I have an array of dictionary, here's an example: { { Category = "Category 4"; Comp = "Category 4"; Depth = 02; Grade = New; Length = 02; Location = "Thousand Oaks, CA"; Name = "3ply Mat"; Owner = "Owner 3"; PUP = 2; Status = Shipped; "Unit Number" = 20110507113852351; Width = 02; }, { Category = "Category 4"; Comp = "Category 4"; Depth = 02; Grade = New; Length = 02; Location = "Thousand Oaks, CA"; Name = "3ply Mat

问题 I have this relationship: player <—>> games <<—> quiz and want to get all quiz not in a game of a player, like SELECT * FROM ZQUIZ WHERE Z_PK NOT IN (SELECT ZQUIZ FROM ZGAME WHERE ZPLAYER == 1) Can anybody help? 回答1: This can be done with a SUBQUERY clause. If myPlayer is the player in question: let predicate = NSPredicate(format:"SUBQUERY(games,$g, $g.player == %@).@count == 0", myPlayer) 来源： https://stackoverflow.com/questions/35688892/nspredicate-with-subquery

问题 Hello guys i have an array of dictionary, can you guys tell me how can i filter this data based on dictionary keys. ( { "mall_id" = M0550; "mall_name" = "Amrita Shopping Complex"; }, { "mall_id" = M0509; "mall_name" = "Ashoka Market"; }, { "mall_id" = M0943; "mall_name" = "Biju Pattnaik Commercial Complex"; }, { "mall_id" = M0457; "mall_name" = "BMC Bhawani Mall"; }, { "mall_id" = M0460; "mall_name" = "BMC Keshari Mall"; }, { "mall_id" = M0571; "mall_name" = "BMC Market Complex"; }, { "mall

问题 Simple question regarding NSPredicate's. I'm trying to construct my predicate with "passed in" values like so : NSPredicate* currentPredicate = [NSPredicate predicateWithFormat:@"%@ == %@",key,[changesDict valueForKey:@"Id"] ]; However, I haven't been able to get this to work correctly. If I insert the actual value I pass through it does work though. So this works : NSPredicate* currentPredicate = [NSPredicate predicateWithFormat:@"contactId == %@",[changesDict valueForKey:@"Id"] ]; (Notice i

问题 I always get the following error when trying to filter my Realm database using NSPredicate : Property 'text' is not a link in object of type 'getType' I want to filter my Realm database to show only the items that have some specific text in them. This is what I've tried: let realm = try! Realm() let predicate = NSPredicate(format: "typez.text.filter = 'special'") let filterThis = realm.objects(Publication).filter(predicate) print(filterThis) The relevant portion of my model classes is: class

问题 I have an array of objects and each has an id, and i want to get all items where item.objectID contains in an array of ids, how can i get that result ? What i tried to do but i have an error on creating predicateWithFormat: Unable to parse the format string : NSString *predicateFormat = [NSString stringWithFormat:@"SELF.itemID CONTAIN IN (1,2,3,4,5,6,7,8)"]; NSPredicate *predicate = [NSPredicate predicateWithFormat: predicateFormat]; filteredData = [localData filteredArrayUsingPredicate