如何使用核心繪圖沿X軸繪製NSDate

Question

我已經嘗試通過核心繪圖中的所有示例，尤其是日期繪圖示例，但仍然困在實施沿着x軸數小時的繪圖。請幫我找出我錯在哪裏。

問題，我面對：

• 未能與均勻分佈小時，以獲得軸（按小時計算，0900 1000，....）
• ，當我將其存儲到plotData陣列，當繪製圖形時，所有的x值都是0.我的意思是，所有的值都只繪製在y軸上。 x值不存儲。

的代碼如下：

NSDateFormatter *dateFormatter1 = [[[NSDateFormatter alloc] init] autorelease]; 
[dateFormatter1 setDateFormat:@"HH:mm a"]; 
NSTimeInterval oneDay = 24 * 60 * 60; 
NSTimeInterval xLow = 0.0f; 

//This part is used to set up the plot space. 
CPXYPlotSpace *plotSpace = (CPXYPlotSpace *)graph.defaultPlotSpace; 
plotSpace.allowsUserInteraction=YES; 
plotSpace.xRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(xLow) 
               length:CPDecimalFromFloat(oneDay)]; 


    CPXYAxisSet *axisSet = (CPXYAxisSet *)graph.axisSet; 
CPXYAxis *x=axisSet.xAxis; 
x.majorIntervalLength = CPDecimalFromFloat(1*60*60); 
x.minorTicksPerInterval = 0; 
x.axisLineStyle = lineStyle; 
x.majorTickLength = 7.0f; 
//x.visibleRange=xAxisRange; 

CPTimeFormatter *timeFormatter = [[[CPTimeFormatter alloc] 
            initWithDateFormatter:dateFormatter1] autorelease]; 
Chirp *retValue=[someTemp objectAtIndex:0]; 
NSDate *tempDate=retValue.startingAt; 
timeFormatter.referenceDate = tempDate; 
x.labelFormatter = timeFormatter; 
x.orthogonalCoordinateDecimal=CPDecimalFromString(@"0"); 


    NSMutableArray *newData = [NSMutableArray array]; 
NSUInteger i; 
for (i = 0; i < [someTemp count]; i++) 
{ 
    Chirp *retValue=[[Chirp alloc]init]; 
    retValue=[someTemp objectAtIndex:i]; 
    NSDate *tempDate=retValue.startingAt; 
    NSString *dateFromString=[dateFormatter1 stringFromDate:tempDate]; 
    NSLog(@"%@", dateFromString); 
    id x=dateFromString; 
    id y=[NSDecimalNumber numberWithFloat:[retValue.chipCount floatValue]]; 
    [newData addObject: 
    [NSDictionary dictionaryWithObjectsAndKeys: 
     x, [NSNumber numberWithInt:CPScatterPlotFieldX], 
     y, [NSNumber numberWithInt:CPScatterPlotFieldY], 
     nil]]; 
} 
plotData = newData; 


-(NSUInteger)numberOfRecordsForPlot:(CPPlot *)plot 
{ 
return plotData.count; 
} 

-(NSNumber *)numberForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index 
{ 
NSDecimalNumber *num = [[plotData objectAtIndex:index] objectForKey:[NSNumber numberWithInt:fieldEnum]]; 
return num; 
} 

Answer 1

你需要爲x軸創建自定義標籤。請參閱core-plot的條形圖示例。它有自定義標籤。這樣你可以顯示小時，日期或任何你想要的東西。

Answer 2

沒關係......！我找到了解決方案。我使我的x軸使用自定義標籤（如Rahul Vyas所建議的）。這解決了我面臨的一個問題。而對於另一個問題，我試圖從NSDate使用NSDateformatter和字符串獲取字符串。我張貼下面的代碼。希望它有助於某個人。 用於在x軸上使用時間自定義標籤的代碼，這在條形圖示例中已經存在。

-(void)configureXAxisForGraph:(CPXYGraph*)graphForAxis 
{ 
CPXYAxisSet *axisSet = (CPXYAxisSet *)graph.axisSet; 
CPXYAxis *x=axisSet.xAxis; 
x.majorIntervalLength = [[NSDecimalNumber decimalNumberWithString:@"1"] decimalValue]; 
CPPlotRange *xAxisRange=[CPPlotRange plotRangeWithLocation:CPDecimalFromString(@"0.0") length:CPDecimalFromString(@"24.0")]; 
x.minorTicksPerInterval = 4; 
x.majorTickLineStyle = lineStyle; 
x.minorTickLineStyle = lineStyle; 
x.axisLineStyle = lineStyle; 
x.minorTickLength = 5.0f; 
x.majorTickLength = 7.0f; 
x.visibleRange=xAxisRange; 
x.orthogonalCoordinateDecimal=CPDecimalFromString(@"0"); 
x.title=@"Hours"; 
x.titleOffset=47.0f; 
x.labelRotation=M_PI/4; 
x.labelingPolicy=CPAxisLabelingPolicyNone; 
NSArray *customTickLocations = [NSArray arrayWithObjects:[NSDecimalNumber numberWithInt:3], [NSDecimalNumber numberWithInt:6], [NSDecimalNumber numberWithInt:9], [NSDecimalNumber numberWithInt:12], 
           [NSDecimalNumber numberWithInt:15], [NSDecimalNumber numberWithInt:18], [NSDecimalNumber numberWithInt:21], [NSDecimalNumber numberWithInt:24],nil]; 
NSArray *xAxisLabels = [NSArray arrayWithObjects:@"3 AM", @"6 AM", @"9 AM", @"12PM", @"3 PM",@"6 PM",@"9 PM", @"12 AM", nil]; 
NSUInteger labelLocation = 0; 
NSMutableArray *customLabels = [NSMutableArray arrayWithCapacity:[xAxisLabels count]]; 
for (NSNumber *tickLocation in customTickLocations) 
{ 
    CPAxisLabel *newLabel = [[CPAxisLabel alloc] initWithText: [xAxisLabels objectAtIndex:labelLocation++] textStyle:x.labelTextStyle]; 
    newLabel.tickLocation = [tickLocation decimalValue]; 
    newLabel.offset = x.labelOffset + x.majorTickLength; 
    newLabel.rotation = M_PI/4; 
    [customLabels addObject:newLabel]; 
    [newLabel release]; 
} 
x.axisLabels = [NSSet setWithArray:customLabels]; 
} 

這裏是代碼對我來說繪製數值和時間（小時）的值。

self.dataToBePlotted = [NSMutableArray array]; 
NSUInteger i; 
for (i = 0; i < [dummyDataArray count]; i++) 
{ 
    Chirp *retValue=[[Chirp alloc]init]; 
    retValue=[dummyDataArray objectAtIndex:i]; 
    NSDate *tempDate=retValue.startingAt; 
    NSString *dateFromString=[dateFormatter1 stringFromDate:tempDate]; 
    NSLog(@"%@", dateFromString); 
    id x=dateFromString; 
    id y=[NSDecimalNumber numberWithFloat:[retValue.chipCount floatValue]]; 
    [self.dataToBePlotted addObject: 
    [NSDictionary dictionaryWithObjectsAndKeys: 
     x, [NSNumber numberWithInt:CPScatterPlotFieldX], 
     y, [NSNumber numberWithInt:CPScatterPlotFieldY], 
     nil]]; 
} 
self.plotData = self.dataToBePlotted; 


-(NSUInteger)numberOfRecordsForPlot:(CPPlot *)plot 
{ 
    return [plotData count]; 
} 

-(NSNumber *)numberForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index 
{ 
    NSDecimalNumber *num = [[plotData objectAtIndex:index] objectForKey:[NSNumber numberWithInt:fieldEnum]]; 
    return num; 
}