objective-c - NSPredicate 中的多个条件

Question

如何在 NSPredicate 中使用多个条件？

我正在使用它，但在返回的数组中没有得到任何东西。

NSPredicate *placePredicate = [NSPredicate predicateWithFormat:@"place CONTAINS[cd] %@ AND category CONTAINS[cd] %@ AND ((dates >= %@) AND (dates <= %@)) AND ((amount >= %f) AND (amount <= %f))",placeTextField.text,selectedCategory,selectedFromDate,selectedToDate,[amountFromTextField.text floatValue],[amountToTextField.text floatValue]];

NSArray *placePredicateArray = [dataArray filteredArrayUsingPredicate:placePredicate];

NSLog(@"placePredicateArray %@", placePredicateArray);

数量和类别有时可以为空。我应该如何构造 NSPredicate？

Answer 1

您可以使用其他 NSPredicate 对象和 NSCompoundPredicate 类构建您的 placesPredicate

类似的东西:

NSPredicate *p1 = [NSPredicate predicateWithFormat:@"place CONTAINS[cd] %@", placeTextField.text];
NSPredicate *p2 = [NSPredicate predicateWithFormat:@"category CONTAINS[cd] %@", selectedCategory];
NSPredicate *p3 = [NSPredicate predicateWithFormat:@"(dates >= %@) AND (dates <= %@)", selectedFromDate,selectedToDate];
NSPredicate *p4 = [NSPredicate predicateWithFormat:@"(amount >= %f) AND (amount <= %f)", [amountFromTextField.text floatValue],[amountToTextField.text floatValue]]; 

NSPredicate *placesPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:@[p1, p2, p3, p4]];

现在，如果您缺少类别，例如您可以使用虚拟 YES 谓词来替换它:

NSPredicate *p2;
if (selectedCategory) {
    p2 = [NSPredicate predicateWithFormat:@"category CONTAINS[cd] %@", selectedCategory];
} else {
    p2 = [NSPredicate predicateWithBool:YES]
}