1 前言
使用 CGAffineTransformMakeRotation/CGContextRotateCTM函數來創建一個仿射旋轉變換。

2 代碼實例
ZYViewControllerView.m

[plain] - (void)drawRect:(CGRect)rect{ 
    /* Create the path first. Just the path handle. */ 
    CGMutablePathRef path = CGPathCreateMutable(); 
    /* Here are our rectangle boundaries */ 
    CGRect rectangle = CGRectMake(10.0f,10.0f, 200.0f, 300.0f); 
    /* Add the rectangle to the path */ 
    CGPathAddRect(path,NULL, rectangle); 
    /* Get the handle to the current context */ 
    CGContextRef currentContext = UIGraphicsGetCurrentContext(); 
    /* Save the state of the context to revert back to how it was at this state, later */ 
    CGContextSaveGState(currentContext); 
    //順時針旋轉45度 
    CGContextRotateCTM(currentContext,(45.0f * M_PI) / 180.0f); 
    /* Add the path to the context */ 
    CGContextAddPath(currentContext, path); 
    /* Set the fill color to cornflower blue */ 
    [[UIColor colorWithRed:0.20f green:0.60f blue:0.80f alpha:1.0f] setFill]; 
    /* Set the stroke color to brown */ 
    [[UIColor brownColor] setStroke]; 
    /* Set the line width (for the stroke) to 5 */ 
    CGContextSetLineWidth(currentContext,5.0f); 
    /* Stroke and fill the path on the context */ 
    CGContextDrawPath(currentContext, kCGPathFillStroke); 
    /* Dispose of the path */ 
    CGPathRelease(path); 
    /* Restore the state of the context */ 
    CGContextRestoreGState(currentContext); 
}