Question

这是我的代码，其中每行都在iPad模拟器中运行应用程序时给出了“无效上下文”错误。 “self.Frame = frame之后的每个语句;给出错误。如何修复它？

- (void)makeFrame:(CGRect)frame number:(NSInteger) number color:(UIColor *) color {

    float rd1 = 225.00/255.00;
    float gr1 = 102.00/255.00;
    float bl1 = 0.00/255.00;

    float rd2 = 225.00/255.00;
    float gr2 = 153.00/255.00;
    float bl2 = 0.00/255.00;

    self.frame = frame;
    self.backgroundColor = [UIColor colorWithRed:rd1 green:gr1 blue:bl1 alpha:1.0]; 
    [[self layer] setBorderColor:[[UIColor blackColor] CGColor]]; 
    [[self layer] setBorderWidth:0.5];  
    [[self layer] setCornerRadius:10]; 
    self.tag = number;  //  set each button's tag
    [self setClipsToBounds: YES];

    //  do date label
    date = [[UILabel alloc]initWithFrame:CGRectMake(10, 2, 65, 40 )]; 
    date.backgroundColor = [UIColor clearColor]; //  x  y   w   h
    date.textColor = [UIColor colorWithRed:rd2 green:gr2 blue:bl2 alpha:1.0];
    date.text = [NSString stringWithFormat:@"%d", number];
    date.font = [UIFont boldSystemFontOfSize:40];
    //   date.alpha = 0.2;
    [self addSubview:date];
}

这是调用makeFrame的代码：

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    allButtons = [NSMutableArray array];
    for(int k = 40, m = 0; m < 6; m++, k+= 42)   //  this controls the vertical distance between rows
        for(int i = 0, j=32; i < 7; i++, j+=102) {  //  this controls the size and horizontal distance
            calendarButton *cb= [calendarButton buttonWithType:UIButtonTypeCustom];
            [cb makeFrame:CGRectMake(j, k, 100, 40) number: allButtons.count+1 color:[UIColor orangeColor]];
            //                       x  y   w   h
            [self.view addSubview:cb];
            [allButtons addObject:cb];  // put it in the array
        }

    calendarButton *cb= [calendarButton buttonWithType:UIButtonTypeCustom];
    [cb drawRect:CGRectMake(0,0, 100, 40)];   //  150

Answer 1

您正尝试访问视图控制器中的视图属性。在您的情况下，self是UIViewController（或sublcass），将其更改为self.view以访问视图

E.g。

self.view.frame = frame;

Answer 2

您手动调用drawRect，我怀疑这是导致此问题。来自文档：

您不应该直接自己调用此方法。要使部分视图无效，从而导致重新绘制该部分，请改为调用setNeedsDisplay或setNeedsDisplayInRect:方法。

但在这种情况下，这看起来并不必要。该视图已添加为您视图的子视图;它会在你的视图呈现时自动绘制。

为什么每行代码都给我“无效的上下文”？

2 个答案: