为什么我的 CGPoint 不能正确保存在 NSMutable 数组中？
因此，我的代码基于以下位置找到的答案： 如何以简单的方式将 CGPoint 对象添加到 NSArray 中？
我的代码现在如下所示：
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch * touch = [touches anyObject];
locationOne = [touch locationInView: [UIApplication sharedApplication].keyWindow];
NSLog(@"In touchesBegan");
NSLog(@"x is: %.3f. y is: %.3f", locationOne.x, locationOne.y);
[points addObject:[NSValue valueWithCGPoint:locationOne]];
NSValue *val = [points objectAtIndex:[points count]];
CGPoint p = [val CGPointValue];
NSLog(@"in points array: x is: %.3f, y is: %.3f", p.x ,p.y);
}
2011-06-16 13:21:57.367 canvas_test[7889:307] In touchesBegan
2011-06-16 13:21:57.371 canvas_test[7889:307] x is: 115.000. y is: 315.500
2011-06-16 13:21:57.374 canvas_test[7889:307] in points array: x is: 0.000, y is: 0.000
2011-06-16 13:22:00.982 canvas_test[7889:307] In touchesBegan
2011-06-16 13:22:00.985 canvas_test[7889:307] x is: 274.500. y is: 386.000
2011-06-16 13:22:00.988 canvas_test[7889:307] in points array: x is: 0.000, y is: 0.190
2011-06-16 13:22:11.476 canvas_test[7889:307] In touchesBegan
2011-06-16 13:22:11.480 canvas_test[7889:307] x is: 105.500. y is: 140.500
2011-06-16 13:22:11.483 canvas_test[7889:307] in points array: x is: 0.000, y is: 0.190
有人知道可能会出现什么问题吗？
编辑：
我注意到，每当我检查我的点数时，它总是为 0。有没有办法检查我是否正确初始化了 NSMutableArray？我用 点= [[NSMutableArray alloc] init]; 在 init 函数中，并且有 NSMutableArray *points；在我的 .h 文件中。我需要做更多的事情来启动 NSMutableArray 吗？
So, I've based my code off of the answer found at: How can I add CGPoint objects to an NSArray the easy way?
My code now reads like:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch * touch = [touches anyObject];
locationOne = [touch locationInView: [UIApplication sharedApplication].keyWindow];
NSLog(@"In touchesBegan");
NSLog(@"x is: %.3f. y is: %.3f", locationOne.x, locationOne.y);
[points addObject:[NSValue valueWithCGPoint:locationOne]];
NSValue *val = [points objectAtIndex:[points count]];
CGPoint p = [val CGPointValue];
NSLog(@"in points array: x is: %.3f, y is: %.3f", p.x ,p.y);
}
2011-06-16 13:21:57.367 canvas_test[7889:307] In touchesBegan
2011-06-16 13:21:57.371 canvas_test[7889:307] x is: 115.000. y is: 315.500
2011-06-16 13:21:57.374 canvas_test[7889:307] in points array: x is: 0.000, y is: 0.000
2011-06-16 13:22:00.982 canvas_test[7889:307] In touchesBegan
2011-06-16 13:22:00.985 canvas_test[7889:307] x is: 274.500. y is: 386.000
2011-06-16 13:22:00.988 canvas_test[7889:307] in points array: x is: 0.000, y is: 0.190
2011-06-16 13:22:11.476 canvas_test[7889:307] In touchesBegan
2011-06-16 13:22:11.480 canvas_test[7889:307] x is: 105.500. y is: 140.500
2011-06-16 13:22:11.483 canvas_test[7889:307] in points array: x is: 0.000, y is: 0.190
Does anybody have any idea what could possibly be going wrong?
edit:
I've noticed that anytime I check my points count, it's always at 0. Is there a way of checking whether I initialized my NSMutableArray correctly? I use
points = [[NSMutableArray alloc] init];
in the init function, and have NSMutableArray *points; in my .h file. Do I need to do anything more to initiate the NSMutableArray?
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我很惊讶这不会崩溃。您正在读取超出数组末尾的内容：
这应该是：
或
I'm surprised this doesn't crash. You're reading beyond the end of the array:
This should be:
or
[points objectAtIndex:[points count]]始终超出范围。数组中的最后一个对象将位于索引[points count] - 1处。或者，您可以只使用
NSValue *val = [points lastObject]。[points objectAtIndex:[points count]]will always be out of range. The last object in the array will be at index[points count] - 1.Alternatively you could just use
NSValue *val = [points lastObject].