我昨天问了这个问题，得到了Eric Skroch的大力帮助。然而，在查看了Core Plot网站上的所有文档以及一些示例后，我仍然有点困惑。所以我将发布到目前为止的代码，看看是否有人能帮我更多。也许孙也会更容易提供帮助。我的问题是，我需要删除一个绘图，然后在选项卡应用程序中用另一个绘图替换它。Eric和其他人说要使用reloadData方法。但是我不知道在我的代码中可以在哪里使用它？这是我的头文件和实现文件。
#import <UIKit/UIKit.h>
#import "CorePlot-CocoaTouch.h"
@interface GraphViewController : UIViewController <CPTPlotDataSource>
@property (nonatomic, strong) CPTGraphHostingView *hostView;
@property (nonatomic, strong) NSMutableArray *myData;
@property (nonatomic) float XAXISMIN;
@property (nonatomic) float XAXISMAX;
@property (nonatomic) float YAXISMIN;
@property (nonatomic) float YAXISMAX;
@property (strong, nonatomic) IBOutlet UILabel *noGraph;
@end
和
#import "GraphViewController.h"
#import "MyVariables.h" // a singleton class for my variables
@interface GraphViewController ()
@end
@implementation GraphViewController
@synthesize hostView = _hostView;
@synthesize myData = _myData;
@synthesize XAXISMIN;
@synthesize XAXISMAX;
@synthesize YAXISMAX;
@synthesize noGraph;
@synthesize YAXISMIN;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[noGraph setText:@""];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
MyVariables *sharedVariables2 = [MyVariables sharedVariables2];
float a = [sharedVariables2.AA floatValue];
MyVariables *sharedVariables3 = [MyVariables sharedVariables3];
float b = [sharedVariables3.BB floatValue];
MyVariables *sharedVariables4 = [MyVariables sharedVariables4];
float c = [sharedVariables4.CC floatValue];
float d = (4.0f)*a*c;
float e = (b*b);
float f = (e - d);
float g = sqrtf(f);
float h = -b;
float i = h + g;
float ii = h - g;
float j = i/(2*a);
float k = ii/(2*a);
// Define x max and min with answers to quad
XAXISMIN = j - (5.0);
XAXISMAX = k + (5.0);
// Find range for the y axis STILL NEEDS WORK!
// maybe if statement for negatives
float z = c - ((b*b)/((4.0f)*a));
YAXISMAX = z + 10.0f;
YAXISMIN = -z;
float inc = (XAXISMAX - XAXISMIN) / 100.0f;
float l = XAXISMIN;
if ((isnan(g)) || (a == 0))
{
[noGraph setText:@"This is not graphable"];
[_hostView setHidden:YES];
}
else
{
NSMutableArray *data = [NSMutableArray array];
for (int i = 0; i < 100; i ++)
{
float y = (a * (l*l)) + (b * l) + c;
NSString *str4 = [NSString stringWithFormat:@"%.3f", l];
NSString *str5 = [NSString stringWithFormat:@"%.3f", y];
NSLog(@"Our X and Y are : %@, %@", str4, str5);
[data addObject:[NSValue valueWithCGPoint:CGPointMake(l, y)]];
l = l + inc;
}
self.myData = data; // put that data array into the array you synthesized
[self initPlot];
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (void)viewDidUnload
{
[self setNoGraph:nil];
[super viewDidUnload];
// Release any retained subviews of the main view.
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
- (NSUInteger)numberOfRecordsForPlot:(CPTPlot *)plot
{
return [_myData count];
}
- (NSNumber *)numberForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex: (NSUInteger)index
{
if ([plot.identifier isEqual:@"Your data"])
{
NSValue *value = [self.myData objectAtIndex:index];
CGPoint point = [value CGPointValue];
// FieldEnum determines if we return an X or Y value.
if (fieldEnum == CPTScatterPlotFieldX)
{
return [NSNumber numberWithFloat:point.x];
}
else // Y-Axis
{
return [NSNumber numberWithFloat:point.y];
}
}
return [NSNumber numberWithFloat:0];
}
- (void)initPlot
{
[self configureHost];
[self configureGraph];
[self configurePlots];
[self configureAxes];
}
- (void)configureHost
{
self.hostView = [(CPTGraphHostingView *) [CPTGraphHostingView alloc] initWithFrame:self.view.bounds];
self.hostView.allowPinchScaling = YES;
[self.view addSubview:self.hostView];
}
- (void)configureGraph
{
// 1 - Create graph
CPTGraph *graph = [[CPTXYGraph alloc] initWithFrame:self.hostView.bounds];
self.hostView.hostedGraph = graph;
// 2 - Set graph title
NSString *title = @"Your Quadratic";
graph.title = title;
// 3 - Create and set text style
CPTMutableTextStyle *titleStyle = [CPTMutableTextStyle textStyle];
titleStyle.color = [CPTColor whiteColor];
titleStyle.fontName = @"Helvetica-Bold";
titleStyle.fontSize = 16.0f;
graph.titleTextStyle = titleStyle;
graph.titlePlotAreaFrameAnchor = CPTRectAnchorTop;
graph.titleDisplacement = CGPointMake(0.0f, 10.0f);
// 4 - Set padding for plot area
[graph.plotAreaFrame setPaddingTop:30.0f];
[graph.plotAreaFrame setPaddingRight:30.0f];
[graph.plotAreaFrame setPaddingLeft:30.0f];
[graph.plotAreaFrame setPaddingBottom:30.0f];
// 5 - Enable use interaction for plot space
CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)graph.defaultPlotSpace;
plotSpace.allowsUserInteraction = YES;
}
- (void)configurePlots
{
// 1 - Get graph and plot spaces and set axis
CPTGraph *graph = self.hostView.hostedGraph;
CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *) graph.defaultPlotSpace;
float xAxisMin = XAXISMIN;
float xAxisMax = XAXISMAX;
float yAxisMin = YAXISMIN;
float yAxisMax = YAXISMAX;
plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(xAxisMin) length:CPTDecimalFromFloat(xAxisMax - xAxisMin)];
plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(yAxisMin) length:CPTDecimalFromFloat(yAxisMax - yAxisMin)];
// 2 - Create the plot
CPTScatterPlot *quadGraph = [[CPTScatterPlot alloc] init];
quadGraph.dataSource = self;
quadGraph.identifier = @"Your data";
CPTColor *quadColor = [CPTColor blackColor];
[graph addPlot:quadGraph toPlotSpace:plotSpace];
// 4 - Create styles and symbols
CPTMutableLineStyle *quadLineStyle = [quadGraph.dataLineStyle mutableCopy];
quadLineStyle.lineWidth = 2.5;
quadLineStyle.lineColor = quadColor;
quadGraph.dataLineStyle = quadLineStyle;
CPTMutableLineStyle *quadSymbolLineStyle = [CPTMutableLineStyle lineStyle];
quadSymbolLineStyle.lineColor = quadColor;
CPTPlotSymbol *quadSymbol = [CPTPlotSymbol ellipsePlotSymbol];
quadSymbol.fill = [CPTFill fillWithColor:quadColor];
quadSymbol.lineStyle = quadSymbolLineStyle;
quadSymbol.size = CGSizeMake(6.0f, 6.0f);
quadGraph.plotSymbol = quadSymbol;
}
- (void)configureAxes
{
// 1 - Create styles
CPTMutableTextStyle *axisTitleStyle = [CPTMutableTextStyle textStyle];
axisTitleStyle.color = [CPTColor whiteColor];
axisTitleStyle.fontName = @"Helvetica-Bold";
axisTitleStyle.fontSize = 12.0f;
CPTMutableLineStyle *axisLineStyle = [CPTMutableLineStyle lineStyle];
axisLineStyle.lineWidth = 2.0f;
axisLineStyle.lineColor = [CPTColor whiteColor];
CPTMutableTextStyle *axisTextStyle = [[CPTMutableTextStyle alloc] init];
axisTextStyle.color = [CPTColor whiteColor];
axisTextStyle.fontName = @"Helvetica-Bold";
axisTextStyle.fontSize = 11.0f;
CPTMutableLineStyle *tickLineStyle = [CPTMutableLineStyle lineStyle];
tickLineStyle.lineColor = [CPTColor whiteColor];
tickLineStyle.lineWidth = 2.0f;
CPTMutableLineStyle *gridLineStyle = [CPTMutableLineStyle lineStyle];
tickLineStyle.lineColor = [CPTColor blackColor];
tickLineStyle.lineWidth = 1.0f;
// 2 - Get axis set
CPTXYAxisSet *axisSet = (CPTXYAxisSet *) self.hostView.hostedGraph.axisSet;
// 3 - Configure x-axis
CPTAxis *x = axisSet.xAxis;
x.title = @"X Axis";
x.titleTextStyle = axisTitleStyle;
x.titleOffset = 1.0f;
x.axisLineStyle = axisLineStyle;
x.labelingPolicy = CPTAxisLabelingPolicyEqualDivisions; //CPTAxisLabelingPolicyNone;
x.labelTextStyle = axisTextStyle;
x.majorTickLineStyle = axisLineStyle;
x.majorTickLength = 4.0f;
x.tickDirection = CPTSignPositive; //CPTSignNegative;
// 4 - Configure y-axis
CPTAxis *y = axisSet.yAxis;
y.title = @"Y Axis";
y.titleTextStyle = axisTitleStyle;
y.titleOffset = -40.0f;
y.axisLineStyle = axisLineStyle;
y.majorGridLineStyle = gridLineStyle;
y.labelingPolicy = CPTAxisLabelingPolicyEqualDivisions;
y.labelTextStyle = axisTextStyle;
y.labelOffset = 16.0f;
y.majorTickLineStyle = axisLineStyle;
y.majorTickLength = 4.0f;
y.minorTickLength = 2.0f;
y.tickDirection = CPTSignNegative;
}
@end
所以我希望有人能让我知道在哪里清除我的数据/绘图，这样我一次只能在图形选项卡上有一个图形。提前感谢！
您应该在-viewDidLoad中初始化和配置图形和宿主视图（即调用-initPlot），以便它只发生一次。在-viewDidAppear中，执行为图形准备所需的任何数据处理，然后调用-reloadData。
好吧，对于关注这个问题的人来说，我已经找到了答案。在埃里克·斯克罗克的大力帮助和指导下，他带领我朝着正确的方向前进。至少我认为我做了正确的事！由于我的图只是用viewDidPear方法创建的，所以我不得不找到另一种方法来使用reloadData。所以我NSLogged了几个方法，看看当视图消失时调用了哪个方法，我发现viewWillDisappear就是其中之一。因此，在这个方法中，我使用了以下内容；
self.hostView.hostedGraph = nil;
和
[_myData removeAllObjects];。
这将清除图形并为下一个图形做好准备，并清空我的数组以做好准备。我很想听听任何人对我的变通方法的看法。我会接受孙的回答，因为如果没有他的帮助，我不会走到这一步。再次感谢！