我有一个在 a 中绘制贝塞尔曲线的应用程序，UIView当我为 Y 设置值时，我需要找到 X 相交。首先，据我了解，没有办法直接找到 a 的点，UIBezierPath但你可以找到一个点CGPath。
首先，如果我“抚摸”我的UIBezierPath（就像我在代码中所做的那样）这实际上是在创建一个 CGPath 还是我需要采取进一步的步骤来实际将它转换为一个 CGPath CGPath？
其次，我想通过提供 Y 的值来找到在 X 处相交的曲线。
我的目的是在用户移动滑块（分别向左或向右移动曲线）时自动计算给定 Y 值的 X。
我的起始显示。
当我当前调整滑块时会发生什么。
我希望我的显示器看起来像什么。
图形视图.h
#import <UIKit/UIKit.h>
@interface GraphView : UIView
{
float adjust;
int x;
int y;
}
- (IBAction)sliderChanged:(id)sender;
- (IBAction)yChanged:(id)sender;
@property (weak, nonatomic) IBOutlet UISlider *sliderValue;
@property (weak, nonatomic) IBOutlet UITextField *xValue;
@property (weak, nonatomic) IBOutlet UITextField *yValue;
@end
图形视图.m
#import "GraphView.h"
@interface GraphView ()
@end
@implementation GraphView
@synthesize sliderValue, xValue, yValue;
- (id)initWithCoder:(NSCoder *)graphView
{
self = [super initWithCoder:graphView];
if (self) {
adjust = 194;
y = 100;
}
return self;
}
- (IBAction)sliderChanged:(id)sender
{
adjust = sliderValue.value;
// Calcualtion of the X Value and setting of xValue.text textField goes here
[self setNeedsDisplay];
}
- (IBAction)yChanged:(id)sender
{
y = yValue.text.intValue;
[self setNeedsDisplay];
[self resignFirstResponder];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch * touch = [touches anyObject];
if(touch.phase == UITouchPhaseBegan) {
y = yValue.text.intValue;
[self setNeedsDisplay];
[yValue resignFirstResponder];
}
}
- (void)drawRect:(CGRect)rect
{
UIBezierPath *lines = [[UIBezierPath alloc] init];
[lines moveToPoint:CGPointMake(0, y)];
[lines addLineToPoint:CGPointMake(200, y)];
[lines addLineToPoint:CGPointMake(200, 280)];
[lines setLineWidth:1];
[[UIColor redColor] setStroke];
float dashPattern[] = {2, 2};
[lines setLineDash:dashPattern count:2 phase:0.0];
[lines stroke];
UIBezierPath *curve = [[UIBezierPath alloc] init];
[curve moveToPoint:CGPointMake(0, 280)];
[curve addCurveToPoint:CGPointMake(280, 0) controlPoint1:CGPointMake(adjust, 280) controlPoint2:CGPointMake(adjust, 0)];
[curve setLineWidth:2];
[[UIColor blueColor] setStroke];
[curve stroke];
}
@end