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问题描述
我想知道是否有可能(以及如何)在Objective-C中提供类似:
的类别Person.Select(@"Name").OrderAsc(@"Name").Where(@"Id").EqualTo(1).And(@"Id").NotEqualTo(2).Load<Array>
这对于我正在做的项目可能非常方便.
我喜欢Django&subsonic中存在的这种编码方式.
推荐答案
简短的答案是，对于Objective-C而言，Linq并不等同，但是您可以将其混合使用SQLITE，NSPREDICATE和COREDATA CALLE，在包装阶段中呼叫，形状为您的喜好.您可能会对核心数据指南， predicate noreferrer"> predicate norefore <>/a>，and 示例典范a>.
从上面的谓词指南:
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Employee"
inManagedObjectContext:managedObjectContext];
[request setEntity:entity];
// assume salaryLimit defined as an NSNumber variable
NSPredicate *predicate = [NSPredicate predicateWithFormat:
@"salary > %@", salaryLimit];
[request setPredicate:predicate];
NSError *error = nil;
NSArray *array = [managedObjectContext executeFetchRequest:request error:&error];
其他推荐答案
我为目标C创建了自己的Linq-Style API，它是 github上可用 .您的特定示例看起来像这样:
NSArray* results = [[[people where:^BOOL(id person) {
return [person id] == 1 && [person id] != 2;
}]
select:^id(id person) {
return [person name];
}]
sort];
其他推荐答案
有一个比较窗户和可可的方法的acticle.可可使用关键路径和nspredicate ....
问题描述
I wonder if it is possible (and how) to provide a class in Objective-C with something like:
Person.Select(@"Name").OrderAsc(@"Name").Where(@"Id").EqualTo(1).And(@"Id").NotEqualTo(2).Load<Array>
That could be very handy for a project I'm doing.
I like this way of coding present in Django & SubSonic.
推荐答案
The short answer is that there is not an equivalent to Linq for Objective-C but you can fake it with a mix of SQLite, NSPredicate and CoreData calls in a wrapper class shaped to your liking. You'd probably be interested in the core data guide, the predicate guide, and this example code.
From the above predicate guide:
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Employee"
inManagedObjectContext:managedObjectContext];
[request setEntity:entity];
// assume salaryLimit defined as an NSNumber variable
NSPredicate *predicate = [NSPredicate predicateWithFormat:
@"salary > %@", salaryLimit];
[request setPredicate:predicate];
NSError *error = nil;
NSArray *array = [managedObjectContext executeFetchRequest:request error:&error];
其他推荐答案
I created my own Linq-style API for Objective C, which is available on github. Your specific example would look something like this:
NSArray* results = [[[people where:^BOOL(id person) {
return [person id] == 1 && [person id] != 2;
}]
select:^id(id person) {
return [person name];
}]
sort];
其他推荐答案
There is an acticle comparing the Windows and Cocoa ways of doing this. Cocoa uses Key Paths And NSPredicate....
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