文字描边可以达到文字描一圈白边的效果

gistfile1.m

//继承UILabel以后重载drawTextInRect
 
- (void)drawTextInRect:(CGRect)rect {
 
   CGSize shadowOffset = self.shadowOffset;
   UIColor *textColor = self.textColor;
 
   CGContextRef c = UIGraphicsGetCurrentContext();
   CGContextSetLineWidth(c, 1);
   CGContextSetLineJoin(c, kCGLineJoinRound);
 
   CGContextSetTextDrawingMode(c, kCGTextStroke);
   self.textColor = [UIColor whiteColor];
   [super drawTextInRect:rect];
 
   CGContextSetTextDrawingMode(c, kCGTextFill);
   self.textColor = textColor;
   self.shadowOffset = CGSizeMake(0, 0);
   [super drawTextInRect:rect];
 
   self.shadowOffset = shadowOffset;
 
}