How to get a black line on a transparent UIView - uiview

Question

I have to draw a black line on a transparent UIView, but despite having set the alpha of the line equal to 1, however this takes the degree of transparency of UIView. how can I do?
#import <UIKit/UIKit.h>
#interface FinalAlgView : UIView{
#private
//....
CGFloat lineWidth;
UIColor *lineColor;
UIImage *curImage;
CGMutablePathRef path;
}
#property (nonatomic, retain) UIColor *lineColor;
#property (readwrite) CGFloat lineWidth;
#property (assign, nonatomic) BOOL empty;
in implementation
#define DEFAULT_COLOR [UIColor colorWithRed:127.0/255.0 green:255.0/255.0 blue:0/255.0 alpha:0.6];
#define DEFAULT_WIDTH 20.0f
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.frame = CGRectMake(0, 0, 1024, 768);
self.lineWidth = DEFAULT_WIDTH;
self.lineColor = DEFAULT_COLOR;
self.empty = YES;
path = CGPathCreateMutable();
self.alpha=0.3;
self.opaque = NO;
}
return self;
}
- (void)drawRect:(CGRect)rect {
[[UIColor grayColor] set];
UIRectFill(rect);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextAddPath(context, path);
CGContextSetLineCap(context, kCGLineCapRound);
CGContextSetLineWidth(context, self.lineWidth);
CGContextSetStrokeColorWithColor(context, self.lineColor.CGColor);
CGContextStrokePath(context);
self.empty = NO;
}

Answer 1

you have to put the setting the alpha of UIView in drawRect and not in initWithFrame
NO
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.alpha=0.3;
}
return self;
}
YES
- (void)drawRect:(CGRect)rect {
[[UIColor colorWithRed:200.0/225.0 green:200.0/255.0 blue:200.0/255.0 alpha:0.0]set];
}