Tablo görünümünde arka plan üzerinde degrade yerleştirme

Question

Tablo görünümü hücrelerim arka planına birkaç yolla bir degrade koymaya çalışıyorum ve hiçbiri işe yaramıyor. Quarz çekirdekli grafik şeyleri ile çizmeye çalışıyorum, arka plan çıkışını IB üzerinde farklı bir görünüme koyup, arkadan görüntü kodu koyar. Hiçbiri arka tarafta görünmüyor, yanlış olanı anlamıyorum. Gerekirse detaylandırırım, teşekkürler!

Answer 1

this question'da bir kod buldum ve uygulamam ile çalışacak şekilde uyarlandı. Hem düz hem de gruplandırılmış tablolarla harika çalışır.

// 
// UAGradientCellBackgroundLayer.h 
// 

#import <Foundation/Foundation.h> 
#import <UIKit/UIKit.h> 

#import <QuartzCore/QuartzCore.h> 

@class UAGradientCellBackgroundView; 

@interface UAGradientCellBackgroundLayer : CAGradientLayer { 
    CGFloat  *colorComponents; 
    BOOL  _override; 
} 

@property(nonatomic,assign) BOOL override; 

- (void)setColorComponents:(CGFloat *)components; 

@end 

// 
// UAGradientCellBackgroundLayer.m 
// 

#import "UAGradientCellBackgroundLayer.h" 
#import "UAGradientCellBackgroundView.h" 

#define TABLE_CELL_BACKGROUND         {1, 1, 1, 1, 204/255.0, 204/255.0, 204/255.0, 1}  // #FFFFFF and #DDDDDD 

@implementation UAGradientCellBackgroundLayer 

@synthesize override = _override; 

/////////////////////////////////////////////////////////////////////////////////////////////////// 
- (id)init { 
    if ((self = [super init])) { 
     colorComponents = NSZoneMalloc(NSDefaultMallocZone(), 8*sizeof(CGFloat)); 
     CGFloat c[8] = TABLE_CELL_BACKGROUND; 
     for (int i = 0; i < 8; i++) { 
      colorComponents[i] = c[i]; 
     } 
     // self.cornerRadius = 10; 
     // self.backgroundColor = [UIColor clearColor].CGColor; 
    } 
    return self; 
} 

- (void) dealloc { 
    NSZoneFree(NSDefaultMallocZone(), colorComponents); 
    [super dealloc]; 
} 
- (void)display { 
    if (_override) { 
     self.colors = 
     [NSArray arrayWithObjects: 
     (id)[UIColor colorWithRed:colorComponents[0] green:colorComponents[1] blue:colorComponents[2] alpha:colorComponents[3]].CGColor, 
     (id)[UIColor colorWithRed:colorComponents[4] green:colorComponents[5] blue:colorComponents[6] alpha:colorComponents[7]].CGColor, 
     nil]; 
    } else { 
     self.colors = 
     [NSArray arrayWithObjects: 
     (id)[UIColor clearColor].CGColor, 
     (id)[UIColor clearColor].CGColor, 
     nil]; 
    } 
    [super display]; 
} 

- (void)setColorComponents:(CGFloat *)components { 
    for (int i = 0; i < 8; i++) { 
     colorComponents[i] = components[i]; 
    } 
} 

@end 

// 
// UAGradientCellBackgroundView.h 
// 

#import <Foundation/Foundation.h> 

#import <UIKit/UIKit.h> 

typedef enum { 
    UAGradientCellBackgroundViewPositionMiddle = 0, 
    UAGradientCellBackgroundViewPositionTop, 
    UAGradientCellBackgroundViewPositionBottom, 
    UAGradientCellBackgroundViewPositionSingle, 
    UAGradientCellBackgroundViewPositionPlain 
} UAGradientCellBackgroundViewPosition; 

@interface UAGradientCellBackgroundView : UIView { 
    UAGradientCellBackgroundViewPosition position; 
    CGFloat colors[8]; 
} 

@property(nonatomic, assign) UAGradientCellBackgroundViewPosition position; 

- (void)setColors:(CGFloat[8])comps; 

@end 

// 
// UAGradientCellBackgroundView.m 
// 

#import "UAGradientCellBackgroundView.h" 
#import "UAGradientCellBackgroundLayer.h" 
#import <QuartzCore/QuartzCore.h> 

#define kDefaultMargin           10 
#define TABLE_CELL_BACKGROUND         {1, 1, 1, 1, 204/255.0, 204/255.0, 204/255.0, 1}  // #FFFFFF and #DDDDDD 

static void addRoundedRectToPath(CGContextRef context, CGRect rect, 
           float ovalWidth,float ovalHeight); 

@implementation UAGradientCellBackgroundView 

@synthesize position; 

////////////////////////////////////////////////////////////////////// 
// PLAIN CELL 
// 
// layerClass 
// 
// returns a CAGradientLayer class as the default layer class for this view 
// 
+ (Class)layerClass { 
    return [UAGradientCellBackgroundLayer class]; 
} 

////////////////////////////////////////////////////////////////////// 
- (void)updateLayer { 
    UAGradientCellBackgroundLayer* layer = (UAGradientCellBackgroundLayer*)self.layer; 
     // This is dramatically faster than calling drawRect. 
    [layer setColorComponents:colors]; 
    layer.override = (self.position == UAGradientCellBackgroundViewPositionPlain); 
    [layer setNeedsDisplay]; 
} 

//////////////////////////////////////////////////////////////////// 
// GROUPED CELL 
- (void)setColors:(CGFloat[8])comps { 
    for (int i = 0; i < 8; i++) { 
     colors[i] = comps[i]; 
    } 
} 

- (BOOL)isOpaque { 
    return YES; 
} 

- (id)initWithFrame:(CGRect)frame { 
    self = [super initWithFrame:frame]; 
    if (self != nil) { 
     CGFloat comps[8] = TABLE_CELL_BACKGROUND; 
     [self setColors:comps]; 
    } 
    return self; 
} 

- (void)debugView:(UIView *)view { 
    NSLog(@"%@ - %@", view.backgroundColor, [[view class] description]); 
    for (UIView* child in view.subviews) { 
     [self debugView:child]; 
    } 
} 

-(void)drawRect:(CGRect)aRect { 
    [super drawRect:aRect]; 
    // Drawing code 
    if (position == UAGradientCellBackgroundViewPositionPlain) { 
     return; 
    } 

    CGContextRef c = UIGraphicsGetCurrentContext(); 

    // TODO - Dirty, Dirty hack to fix the background black corners on pop issue. doesnt handle rotation. 
// CGContextSetFillColorWithColor(c, [UAColor offsetPinstripesColor].CGColor); 
// CGContextFillRect(c, aRect); 

    int lineWidth = 1; 

    CGRect rect = [self bounds]; 
    rect.size.width -= lineWidth; 
    rect.size.height -= lineWidth; 
    rect.origin.x += lineWidth/2.0; 
    rect.origin.y += lineWidth/2.0; 

    CGFloat minx = CGRectGetMinX(rect), midx = CGRectGetMidX(rect), maxx = CGRectGetMaxX(rect); 
    CGFloat miny = CGRectGetMinY(rect), midy = CGRectGetMidY(rect), maxy = CGRectGetMaxY(rect); 
    miny -= 1; 

    CGFloat locations[2] = { 0.0, 1.0 };  
    CGColorSpaceRef myColorspace = CGColorSpaceCreateDeviceRGB(); 
    CGGradientRef myGradient = nil; 

    CGContextSetStrokeColorWithColor(c, [UIColor darkGrayColor].CGColor); 
    CGContextSetLineWidth(c, lineWidth); 
    CGContextSetAllowsAntialiasing(c, YES); 
    CGContextSetShouldAntialias(c, YES); 

    if (position == UAGradientCellBackgroundViewPositionTop) { 
     miny += 1; 

     CGMutablePathRef path = CGPathCreateMutable(); 
     CGPathMoveToPoint(path, NULL, minx, maxy); 
     CGPathAddArcToPoint(path, NULL, minx, miny, midx, miny, kDefaultMargin); 
     CGPathAddArcToPoint(path, NULL, maxx, miny, maxx, maxy, kDefaultMargin); 
     CGPathAddLineToPoint(path, NULL, maxx, maxy); 
     CGPathAddLineToPoint(path, NULL, minx, maxy); 
     CGPathCloseSubpath(path); 

     // Fill and stroke the path 
     CGContextSaveGState(c); 
     CGContextAddPath(c, path); 
     CGContextClip(c); 

     myGradient = CGGradientCreateWithColorComponents(myColorspace, colors, locations, 2); 
     CGContextDrawLinearGradient(c, myGradient, CGPointMake(minx,miny), CGPointMake(minx,maxy), 0); 

     CGContextAddPath(c, path); 
     CGPathRelease(path); 
     CGContextStrokePath(c); 
     CGContextRestoreGState(c); 

    } else if (position == UAGradientCellBackgroundViewPositionBottom) { 
     //maxy -= 1; // -1 for the shadow 

     CGMutablePathRef path = CGPathCreateMutable(); 
     CGPathMoveToPoint(path, NULL, minx, miny); 
     CGPathAddArcToPoint(path, NULL, minx, maxy, midx, maxy, kDefaultMargin); 
     CGPathAddArcToPoint(path, NULL, maxx, maxy, maxx, miny, kDefaultMargin); 
     CGPathAddLineToPoint(path, NULL, maxx, miny); 
     CGPathAddLineToPoint(path, NULL, minx, miny); 
     CGPathCloseSubpath(path); 

     // Fill and stroke the path 
     CGContextSaveGState(c); 
     CGContextAddPath(c, path); 
     CGContextClip(c); 

     myGradient = CGGradientCreateWithColorComponents(myColorspace, colors, locations, 2); 
     CGContextDrawLinearGradient(c, myGradient, CGPointMake(minx,miny), CGPointMake(minx,maxy), 0); 

     CGContextAddPath(c, path); 
     CGPathRelease(path); 
     CGContextStrokePath(c); 
     CGContextRestoreGState(c); 


    } else if (position == UAGradientCellBackgroundViewPositionMiddle) { 

     CGMutablePathRef path = CGPathCreateMutable(); 
     CGPathMoveToPoint(path, NULL, minx, miny); 
     CGPathAddLineToPoint(path, NULL, maxx, miny); 
     CGPathAddLineToPoint(path, NULL, maxx, maxy); 
     CGPathAddLineToPoint(path, NULL, minx, maxy); 
     CGPathAddLineToPoint(path, NULL, minx, miny); 
     CGPathCloseSubpath(path); 

     // Fill and stroke the path 
     CGContextSaveGState(c); 
     CGContextAddPath(c, path); 
     CGContextClip(c); 

     myGradient = CGGradientCreateWithColorComponents(myColorspace, colors, locations, 2); 
     CGContextDrawLinearGradient(c, myGradient, CGPointMake(minx,miny), CGPointMake(minx,maxy), 0); 

     CGContextAddPath(c, path); 
     CGPathRelease(path); 
     CGContextStrokePath(c); 
     CGContextRestoreGState(c); 

    } else if (position == UAGradientCellBackgroundViewPositionSingle) { 
     miny += 1; 
     //maxy -= 1; // -1 for the shadow 

     CGMutablePathRef path = CGPathCreateMutable(); 
     CGPathMoveToPoint(path, NULL, minx, midy); 
     CGPathAddArcToPoint(path, NULL, minx, miny, midx, miny, kDefaultMargin); 
     CGPathAddArcToPoint(path, NULL, maxx, miny, maxx, midy, kDefaultMargin); 
     CGPathAddArcToPoint(path, NULL, maxx, maxy, midx, maxy, kDefaultMargin); 
     CGPathAddArcToPoint(path, NULL, minx, maxy, minx, midy, kDefaultMargin); 
     CGPathCloseSubpath(path); 

     // Shadow 
//  CGContextAddPath(c, path); 
//  CGContextSaveGState(c); 
//  CGContextSetShadow(c, CGSizeMake(0, -1), 1); 
//  CGContextFillPath(c); 

     // Fill and stroke the path 
     CGContextSaveGState(c); 
     CGContextAddPath(c, path); 
     CGContextClip(c); 


     myGradient = CGGradientCreateWithColorComponents(myColorspace, colors, locations, 2); 
     CGContextDrawLinearGradient(c, myGradient, CGPointMake(minx,miny), CGPointMake(minx,maxy), 0); 

     CGContextAddPath(c, path); 
     CGPathRelease(path); 
     CGContextStrokePath(c); 
     CGContextRestoreGState(c); 

    } 
    CGColorSpaceRelease(myColorspace); 
    CGGradientRelease(myGradient); 
    return; 
} 

- (void)setPosition:(UAGradientCellBackgroundViewPosition)newPosition { 
    if (position != newPosition) { 
     position = newPosition; 
     [self updateLayer]; 
    } 
} 

@end 

static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth,float ovalHeight) { 
    float fw, fh; 

    if (ovalWidth == 0 || ovalHeight == 0) {// 1 
     CGContextAddRect(context, rect); 
     return; 
    } 

    CGContextSaveGState(context);// 2 

    CGContextTranslateCTM (context, CGRectGetMinX(rect),// 3 
          CGRectGetMinY(rect)); 
    CGContextScaleCTM (context, ovalWidth, ovalHeight);// 4 
    fw = CGRectGetWidth (rect)/ovalWidth;// 5 
    fh = CGRectGetHeight (rect)/ovalHeight;// 6 

    CGContextMoveToPoint(context, fw, fh/2); // 7 
    CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);// 8 
    CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1);// 9 
    CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1);// 10 
    CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1); // 11 
    CGContextClosePath(context);// 12 

    CGContextRestoreGState(context);// 13 
} 

Kullanım örneği (düz tablo): Bu arka plan olarak neden çalışmaz

#import "UAGradientCellBackgroundView.h" 
CGFloat COLORS[8] = { 0.0/255, 0.0/255, 255.0/255, 1.0, 0.0/255, 0.0/255, 0.0/255, 1.0 } 
... 

- (UITableViewCell *)tableView:(UITableView *)table cellForRowAtIndexPath:(NSIndexPath *)indexPath { 
    NSString *cellID = @"CellID"; 

    // create cell 
    UITableViewCell *cell = (UITableViewCell *)[table dequeueReusableCellWithIdentifier:cellID]; 
    if (cell == nil) { 
     cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellID] autorelease]; 

     UAGradientCellBackgroundView *bgView = [[[UAGradientCellBackgroundView alloc] initWithFrame:CGRectZero] autorelease]; 
     [bgView setBackgroundColor:[UIColor clearColor]]; 
     [bgView setColors:COLORS]; 
     [bgView setPosition:UAGradientCellBackgroundViewPositionPlain]; 
     cell.selectedBackgroundView = bgView; 
     cell.textLabel.backgroundColor = [UIColor clearColor]; 

     cell.imageView.image = [UIImage imageNamed:@"cellimg.png"]; 
    } 

    cell.textLabel.text = @"Text"; 
    return cell; 
}