How to use CGAffineTransformMakeRotation?

问题

I want to draw text use Quartz 2D. The \"menu\" direction is wrong. I want \"Menu\" still readable and have 45 degree with X-axis. Below is my code:

CGContextSelectFont(context, \"Arial\", 12, kCGEncodingMacRoman);
CGContextSetTextDrawingMode(context, kCGTextFill);

CGContextSetRGBFillColor(context, 0, 0, 0, 1); // 6 
CGContextSetRGBStrokeColor(context, 0, 0, 0, 1);

CGContextSetTextMatrix(context, CGAffineTransformMake(1.0,0.0, 0.0, -1.0, 0.0, 0.0));   
CGContextSetTextMatrix(context, CGAffineTransformMakeRotation(45)); 
CGContextShowTextAtPoint(context,10, 10, \"Menu\", 4);

回答1:

CGAffineTransformMakeRotation expects angle in radians, not in degrees.

#define DEGREES_TO_RADIANS(x) (M_PI * (x) / 180.0)
...

CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(45));

回答2:

[view setTransform:CGAffineTransformMakeRotation(M_PI / 2)];

来源：https://stackoverflow.com/questions/5725099/how-to-use-cgaffinetransformmakerotation