objective-c - 为什么每一行代码都给我 "invalid context"？

Question

这是我的代码，在 iPad 模拟器中运行应用程序时，每一行都给我一个“无效上下文”错误。 “self.Frame = frame; 之后的每个语句都给出了错误。我该如何解决？

- (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

您正在手动调用 drawRect，我怀疑这是导致此问题的原因。来自文档:

You should never call this method directly yourself. To invalidate part of your view, and thus cause that portion to be redrawn, call the setNeedsDisplay or setNeedsDisplayInRect: method instead.

不过，在本例中这看起来没有必要。该 View 已添加为您的 View 的 subview ；它会在您的 View 呈现时自动绘制。