学步园

UISearchBar是由两个subView组成的，一个是UISearchBarBackGround,另一个是UITextField. 要IB中没有直接操作背景的属性，在此我总结了几个方法去假改它。

1. 只显示UITextField.采用了layer mask.代码如下：

//first make sure you include core animation so that the compiler will know about your view's layer<br /> #import <QuartzCore/QuartzCore.h><br /> //now make a mask. this is basically just a solid colored shape. When you apply the mask, anywhere where the color is solid will become transparent in your view. i used the excellent Opacity (http://likethought.com/opacity/) to generate this code, but you can do it any way you'd like<br /> @interface SearchMaskLayer : CALayer {<br /> }<br /> @end<br /> @implementation SearchMaskLayer<br /> - (void)drawInContext:(CGContextRef)context<br /> {</p> <p> CGRect imageBounds = CGRectMake(0, 0, 310, 34);<br /> CGRect bounds = imageBounds;<br /> CGFloat alignStroke;<br /> CGFloat resolution;<br /> CGMutablePathRef path;<br /> CGPoint point;<br /> CGPoint controlPoint1;<br /> CGPoint controlPoint2;<br /> UIColor *color;<br /> resolution = 0.5 * (bounds.size.width / imageBounds.size.width + bounds.size.height / imageBounds.size.height);<br /> CGContextSaveGState(context);<br /> CGContextTranslateCTM(context, bounds.origin.x, bounds.origin.y);<br /> CGContextScaleCTM(context, (bounds.size.width / imageBounds.size.width), (bounds.size.height / imageBounds.size.height));<br /> // Layer 1<br /> alignStroke = 0.0;<br /> path = CGPathCreateMutable();<br /> point = CGPointMake(295.0, 32.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> CGPathMoveToPoint(path, NULL, point.x, point.y);<br /> point = CGPointMake(310.0, 17.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> controlPoint1 = CGPointMake(303.229, 32.0);<br /> controlPoint1.x = (round(resolution * controlPoint1.x + alignStroke) - alignStroke) / resolution;<br /> controlPoint1.y = (round(resolution * controlPoint1.y + alignStroke) - alignStroke) / resolution;<br /> controlPoint2 = CGPointMake(310.0, 25.229);<br /> controlPoint2.x = (round(resolution * controlPoint2.x + alignStroke) - alignStroke) / resolution;<br /> controlPoint2.y = (round(resolution * controlPoint2.y + alignStroke) - alignStroke) / resolution;<br /> CGPathAddCurveToPoint(path, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, point.x, point.y);<br /> point = CGPointMake(310.0, 17.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> CGPathAddLineToPoint(path, NULL, point.x, point.y);<br /> point = CGPointMake(295.0, 2.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> controlPoint1 = CGPointMake(310.0, 8.771);<br /> controlPoint1.x = (round(resolution * controlPoint1.x + alignStroke) - alignStroke) / resolution;<br /> controlPoint1.y = (round(resolution * controlPoint1.y + alignStroke) - alignStroke) / resolution;<br /> controlPoint2 = CGPointMake(303.229, 2.0);<br /> controlPoint2.x = (round(resolution * controlPoint2.x + alignStroke) - alignStroke) / resolution;<br /> controlPoint2.y = (round(resolution * controlPoint2.y + alignStroke) - alignStroke) / resolution;<br /> CGPathAddCurveToPoint(path, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, point.x, point.y);<br /> point = CGPointMake(15.0, 2.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> CGPathAddLineToPoint(path, NULL, point.x, point.y);<br /> point = CGPointMake(0.0, 17.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> controlPoint1 = CGPointMake(6.771, 2.0);<br /> controlPoint1.x = (round(resolution * controlPoint1.x + alignStroke) - alignStroke) / resolution;<br /> controlPoint1.y = (round(resolution * controlPoint1.y + alignStroke) - alignStroke) / resolution;<br /> controlPoint2 = CGPointMake(0.0, 8.771);<br /> controlPoint2.x = (round(resolution * controlPoint2.x + alignStroke) - alignStroke) / resolution;<br /> controlPoint2.y = (round(resolution * controlPoint2.y + alignStroke) - alignStroke) / resolution;<br /> CGPathAddCurveToPoint(path, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, point.x, point.y);<br /> point = CGPointMake(0.0, 17.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> CGPathAddLineToPoint(path, NULL, point.x, point.y);<br /> point = CGPointMake(15.0, 32.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> controlPoint1 = CGPointMake(0.0, 25.229);<br /> controlPoint1.x = (round(resolution * controlPoint1.x + alignStroke) - alignStroke) / resolution;<br /> controlPoint1.y = (round(resolution * controlPoint1.y + alignStroke) - alignStroke) / resolution;<br /> controlPoint2 = CGPointMake(6.771, 32.0);<br /> controlPoint2.x = (round(resolution * controlPoint2.x + alignStroke) - alignStroke) / resolution;<br /> controlPoint2.y = (round(resolution * controlPoint2.y + alignStroke) - alignStroke) / resolution;<br /> CGPathAddCurveToPoint(path, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, point.x, point.y);<br /> point = CGPointMake(295.0, 32.0);<br /> point.x = (round(resolution * point.x + alignStroke) - alignStroke) / resolution;<br /> point.y = (round(resolution * point.y + alignStroke) - alignStroke) / resolution;<br /> CGPathAddLineToPoint(path, NULL, point.x, point.y);<br /> CGPathCloseSubpath(path);<br /> color = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:1.0];<br /> [color setFill];<br /> CGContextAddPath(context, path);<br /> CGContextFillPath(context);<br /> CGPathRelease(path);<br /> }<br /> 然后在你的controller中应用这个mask layer到你的UISearchBar<br /> - (void)viewDidLoad {<br /> [super viewDidLoad];<br /> SearchMaskLayer *maskLayer = [[SearchMaskLayer alloc] init];<br /> [maskLayer setFrame:CGRectMake(0, 0, 310, 34)];<br /> [maskLayer setPosition:CGPointMake(162,21)];<br /> [maskLayer setNeedsDisplay];<br /> [self.searchBar.layer setNeedsDisplay];<br /> [self.searchBar.layer setMask:maskLayer];<br /> [maskLayer release];<br /> } 

2. 隐藏背景。非官方的方法。

for (UIView *subview in searchBar.subviews) {<br /> if ([subview isKindOfClass:NSClassFromString(@"UISearchBarBackground")]) {<br /> [subview removeFromSuperview];<br /> break;<br /> }<br /> } 

3. 改变UISearchBar外观。 你可以子类化或category UISearchBar,然后实现两个方法，见代码。

- (void)drawRect:(CGRect)rect {<br /> // UIImage *image = [UIImage imageNamed: @"background.png"];<br /> // [image drawInRect:rect];<br /> }<br /> - (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx {<br /> UIImage *img = [UIImage imageNamed: @"background.png"];<br /> UIImageView *v = [[[UIImageView alloc] initWithFrame:CGRectZero] autorelease];<br /> [v setImage:img];<br /> v.bounds = CGRectMake(0, 0, img.size.width, img.size.height);<br /> NSLog([NSString stringWithFormat:@"%f:%f",img.size.width, img.size.height]);<br /> NSArray *subs = self.subviews;<br /> for (int i = 0; i < [subs count]; i++) {<br /> id subv = [self.subviews objectAtIndex:i];<br /> if ([subv isKindOfClass:NSClassFromString(@"UISearchBarBackground")])<br /> {<br /> CGRect viewRect = [subv frame];<br /> [v setFrame:viewRect];<br /> [self insertSubview:v atIndex:i];<br /> }<br /> }<br /> [v setNeedsDisplay];<br /> [v setNeedsLayout];<br /> } 

UISearchBar也是一个UIView,所以你可以像对待UIView一样对待它。