我正在代码中创建一个 NSPredicateEditor 并尝试实现我所希望的相当简单的任务。基本上,我想显示一个复合 NSPredicateEditorRowTemplate (为用户提供在“以下所有/任何/都不为真”时执行匹配的选项)及其下方的许多相当基本的子行。为此,我构建了 NSPredicateEditor 并绑定(bind)其值,以便在用户编辑谓词时保存更改。
我遇到的问题是,无论如何,我无法使复合 NSPredicateEditorRowTemplate 默认显示为具有单个子行的父行。当我最初创建谓词时,我传递了一个虚假的空谓词,如下所示:
filename BEGINSWITH[cd] ''
为了强制显示复合行,我必须创建两个子行:
filename BEGINSWITH[cd] '' && path ==[cd] ''
作为引用,以下是我构建 NSPredicateEditor 的方法:
NSArray *keyPaths = [NSArray arrayWithObjects:[NSExpression expressionForKeyPath:@"filename"], [NSExpression expressionForKeyPath:@"path"], nil];
NSArray *operators = [NSArray arrayWithObjects:[NSNumber numberWithInteger:NSEqualToPredicateOperatorType],
[NSNumber numberWithInteger:NSNotEqualToPredicateOperatorType],
[NSNumber numberWithInteger:NSBeginsWithPredicateOperatorType],
[NSNumber numberWithInteger:NSEndsWithPredicateOperatorType],
[NSNumber numberWithInteger:NSContainsPredicateOperatorType],
nil];
NSPredicateEditorRowTemplate *template = [[NSPredicateEditorRowTemplate alloc] initWithLeftExpressions:keyPaths
rightExpressionAttributeType:NSStringAttributeType
modifier:NSDirectPredicateModifier
operators:operators
options:(NSCaseInsensitivePredicateOption | NSDiacriticInsensitivePredicateOption)];
NSArray *compoundTypes = [NSArray arrayWithObjects:[NSNumber numberWithInteger:NSNotPredicateType],
[NSNumber numberWithInteger:NSAndPredicateType],
[NSNumber numberWithInteger:NSOrPredicateType],
nil];
NSPredicateEditorRowTemplate *compound = [[NSPredicateEditorRowTemplate alloc] initWithCompoundTypes:compoundTypes];
NSArray *rowTemplates = [NSArray arrayWithObjects:compound, template, nil];
[template release];
[compound release];
predicateEditor = [[NSPredicateEditor alloc] init];
[predicateEditor setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
[predicateEditor setRowTemplates:rowTemplates];
[predicateEditor setCanRemoveAllRows:NO];
[predicateEditor setContinuous:YES];
[predicateEditor setFrame:[[scrollView contentView] bounds]];
// Create a custom binding for our NSPredicateEditor
SIPredicateStringValueTransformer *transformer = [[[SIPredicateStringValueTransformer alloc] init] autorelease];
NSMutableDictionary *bindingOptions = [NSMutableDictionary dictionaryWithObjectsAndKeys:transformer, NSValueTransformerBindingOption, [NSNumber numberWithBool:YES], NSValidatesImmediatelyBindingOption, nil];
[predicateEditor bind:@"value" toObject:self withKeyPath:@"self.filter.predicate" options:bindingOptions];
// Add our NSPredicateEditor to our NSScrollView
[scrollView setDocumentView:predicateEditor];
最佳答案
问题是你给它一个比较谓词。您需要给它一个复合的。
我猜测您的 SIPredicateStringValueTransformer
对象正在获取一个字符串并将其转换为谓词,对吗?它可能正在做这样的事情:
- (id) transformedValue:(id)value {
return [NSPredicate predicateWithFormat:value];
}
您想要做的是保证值转换器不只返回任何旧谓词,而是返回一个复合谓词(即 NSCompoundPredicate
而不是NSComparisonPredicate
)。实现这一点的方法非常简单:
- (id) transformedValue:(id)value {
NSPredicate *p = [NSPredicate predicateWithFormat:value];
if ([p isKindOfClass:[NSComparisonPredicate class]]) {
p = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObject:p]];
}
return p;
}
当您向谓词编辑器提供 NSCompoundPredicate
时,它会显示复合行。当您仅给出比较谓词时,它仅显示适当的比较行。
关于cocoa - 使用 NSPredicateEditor 强制显示复合行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5976244/