NSPredicate filter array

Question

如何使用NSPredicate過濾數組中的對象 - > _ title變量等於變量標題？我嘗試了下面的內容，但它沒有過濾任何東西。

NSMutableArray *array = [[posts mutableCopy] autorelease]; 
NSString *title = [[TBForrstr sharedForrstr] stringForPostType:type]; 
[array filterUsingPredicate:[NSPredicate predicateWithFormat:[NSString stringWithFormat:@"SELF->_title == %@", title]]]; 

Answer 1

確保標題正是數組中的匹配。或者，如果你想成爲更靈活，使其不區分大小寫：

NSMutableArray *array = [[posts mutableCopy] autorelease]; 
NSString *title = [[TBForrstr sharedForrstr] stringForPostType:type]; 
[array filterUsingPredicate:[NSPredicate predicateWithFormat:@"_title == [cd]%@", title]]; 

Answer 2

只需使用類似：

[NSPRedicate predicateWithFormat:@"title LIKE %@",title] 

標題應符合您的_title伊娃通過KVC

Answer 3

這一個是爲我工作 - 發現串繞單引號：

NSArray *posts = [NSArray arrayWithObjects: 
    [NSDictionary dictionaryWithObjectsAndKeys: @"Cat or dog?", @"_title", nil], 
    [NSDictionary dictionaryWithObjectsAndKeys: @"I saved a file, where is it?", @"_title", nil], 
    [NSDictionary dictionaryWithObjectsAndKeys: @"How should I do this?", @"_title", nil], 
nil]; 

NSMutableArray *array = [[posts mutableCopy] autorelease]; 
NSString *title = @"Cat or dog?"; 
[array filterUsingPredicate:[NSPredicate predicateWithFormat:[NSString stringWithFormat:@"SELF._title == '%@'", title]]]; 

NSLog(@"%@", array);