我在ViewDidLoad中写了如下代码
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
-(void)viewDidLoad {
[super viewDidLoad];
NSString *str = [NSString stringWithFormat:@"Veer"];
CGColorSpaceRef rgbColorspace = CGColorSpaceCreateDeviceRGB();
CGFloat values[4] = {55.0, 0.0, 0.0, 1.0};
CGColorRef glowColor = CGColorCreate(rgbColorspace, values);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetShadowWithColor( context, CGSizeMake( 5.0, 0.0 ), 20.0f, glowColor);
[str drawAtPoint:CGPointMake(10.5f, 0.5f) withFont:[UIFont fontWithName:@"Helvetica" size:100.0f]];
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(60, 200, 250, 100)];
[label setBackgroundColor:[UIColor clearColor]];
label.font=[UIFont fontWithName:@"DBLCDTempBlack" size:50.0];
label.textColor = [UIColor colorWithRed:0.0 green:1.0 blue:0.0 alpha:1.0];
[label setText:str];
[self.view addSubview:label];
}
在控制台中我看到了
Testing Clock[3286] <Error>: CGContextSetStyle: invalid context 0x0
Testing Clock[3286] <Error>: CGContextSetFont: invalid context 0x0
Testing Clock[3286] <Error>: CGContextSetTextMatrix: invalid context 0x0
Testing Clock[3286] <Error>: CGContextSetFontSize: invalid context 0x0
Testing Clock[3286] <Error>: CGContextSetTextPosition: invalid context 0x0
Testing Clock[3286] <Error>: CGContextShowGlyphsWithAdvances: invalid context 0x0
最佳答案
您应该将该自定义绘图代码移出 viewDidLoad，并将其移至 drawRect。
如果您想实现自己的 drawRect 方法，您还需要将 View 子类化。
查看此示例:http://ykyuen.wordpress.com/2010/08/27/iphone-uiview-with-border/
关于ios - 这个错误是什么无效上下文0x0？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6597982/