如何通过CGRect过滤NSArray中的CGPoints

Question

我有一个NSArray带CGPoints.我想通过在rect中包含点来过滤这个数组.

我怎样才能NSPredicate表明每个点满足这个谓词:

CGRectContainsPoint(windowRect,point);

这是迄今为止的代码:

NSArray *points = [NSArray arrayWithObjects: [NSValue valueWithCGPoint:pointAtYZero] ,
                                             [NSValue valueWithCGPoint:pointAtYHeight],
                                             [NSValue valueWithCGPoint:pointAtXZero],
                                             [NSValue valueWithCGPoint:pointAtXWidth],
                                             nil];


NSPredicate *inWindowPredicate = [NSPredicate predicateWithFormat:@"CGRectContainsPoint(windowRect, [point CGPointValue])"];
NSArray *filteredPoints = [points filteredArrayUsingPredicate:inWindowPredicate];

Answer 1

您不能使用谓词格式语法执行此操作,但可以使用块:

NSArray *points = ...;
CGRect windowRect = ...;    
NSPredicate *inWindowPredicate = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
    CGPoint point = [evaluatedObject CGPointValue];
    return CGRectContainsPoint(windowRect, point);
}];
NSArray *filteredPoints = [points filteredArrayUsingPredicate:inWindowPredicate];

请注意,无法对Core Data获取请求使用基于块的谓词.