[转载]core-Plot学习二 自定义CorePlot label及majorGridLine莫名其妙消失的Bug

设置corePlot可拖动： 

plotSpace.allowsUserInteraction = YES;  

设置x显示的范围：

plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromInt(8 * oneDay)length:CPTDecimalFromInt(23 * oneDay)];  

设置x轴拖动范围：

plotSpace.globalXRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromInt(0) length:CPTDecimalFromInt(31 * oneDay)];  

禁止corePlot缩放(Self是CPTGraphHostingView)：

    [self setAllowPinchScaling:NO];//禁止缩放  

自定义label：

    x.axisLabels = [self buildLabelTitle];  
    x.labelingPolicy = CPTAxisLabelingPolicyNone;  
      
    //构建30天的label样式  
    - (NSMutableSet*)buildLabelTitle  
    {  
        NSMutableSet *newAxisLabels = [NSMutableSet set];  
          
        CPTMutableTextStyle *textStyleB = [CPTMutableTextStyle textStyle];  
        textStyleB.color = [CPTColor colorWithComponentRed:CPTFloat((float)0x09/0xFF) green:CPTFloat((float)0x31/0xFF) blue:CPTFloat((float)0x4A/0xFF) alpha:CPTFloat(1.0)];  
        NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];  
        [dateFormatter setDateFormat:@"MM.dd"];  
      
        int n = 1;  
        for ( NSUInteger i = 29; i > 0; i--) //从今起前29天  
        {  
            NSTimeInterval secondsPerDay = 24 * 60 * 60 * i;  
            NSDate *ago = [[NSDate alloc] initWithTimeIntervalSinceNow:-secondsPerDay];  
            CPTAxisLabel *newLabel = [[CPTAxisLabel alloc] initWithText:[dateFormatter stringFromDate:ago]  
                                                              textStyle:textStyleB];  
            [ago release];  
            newLabel.tickLocation = CPTDecimalFromUnsignedInteger(n++ * oneDay);  
            newLabel.offset = 5;  
            [self.locationLabels addObject:[NSNumber numberWithInt:(n-1) * oneDay]];  
            [newAxisLabels addObject:newLabel];  
            [newLabel release];  
        }  
          
        //今天  
        CPTMutableTextStyle *textStyleW = [CPTMutableTextStyle textStyle];  
        textStyleW.color = [CPTColor whiteColor];  
        CPTAxisLabel *newLabel = [[CPTAxisLabel alloc] initWithText:@"今日" textStyle:textStyleW];  
        newLabel.tickLocation = CPTDecimalFromUnsignedInteger(oneDay * n);  
        [self.locationLabels addObject:[NSNumber numberWithInt:(n) * oneDay]];  
        newLabel.offset = 5;  
        [newAxisLabels addObject:newLabel];  
        [newLabel release];  
          
        return newAxisLabels;  
    }  

但是写好后发现majorGridLine不见了，之后各种折腾后终于找到原因是：

CPTAxisLabelingPolicyNone       No labels provided; user sets labels and tick locations.

设置这个属性是要自己重新定义majorGridLine位置的

所以需要使用：

    x.majorTickLocations = [NSSet setWithArray:locationLabels];