绘制字符串与图像

借鉴于斯坦福课程

.h

<span style="font-size:18px;">#import <UIKit/UIKit.h>@interface DrawingView : UIView@property (nonatomic) NSInteger rank;@property (nonatomic, strong) NSString *suit;@property (nonatomic) BOOL faceUp;- (void)pinch:(UIPinchGestureRecognizer *)gesture;@end</span>

.m

<span style="font-size:18px;">#import "DrawingView.h"@interface DrawingView ()@property (nonatomic) CGFloat faceCardScaleFactor;@end@implementation DrawingView@synthesize faceCardScaleFactor = _faceCardScaleFactor;//因为同时自定义了setter和getter方法。#define DEFAULT_FACE_CARD_SCALE_FACTOR 0.90- (CGFloat)faceCardScaleFactor{    if (!_faceCardScaleFactor) {        _faceCardScaleFactor = DEFAULT_FACE_CARD_SCALE_FACTOR;    }    return _faceCardScaleFactor;}- (void)setFaceCardScaleFactor:(CGFloat)faceCardScaleFactor{    _faceCardScaleFactor = faceCardScaleFactor;    [self setNeedsDisplay];}- (void)setSuit:(NSString *)suit{    _suit = suit;    [self setNeedsDisplay];}- (void)setRank:(NSInteger)rank{    _rank = rank;    [self setNeedsDisplay];}- (void)setFaceUp:(BOOL)faceUp{    _faceUp = faceUp;    [self setNeedsDisplay];}- (void)pinch:(UIPinchGestureRecognizer *)gesture{    if ((gesture.state == UIGestureRecognizerStateChanged) || (gesture.state == UIGestureRecognizerStateEnded)) {        self.faceCardScaleFactor *= gesture.scale;        gesture.scale = 1.0;    }}// Only override drawRect: if you perform custom drawing.// An empty implementation adversely affects performance during animation.- (NSString *)rankAsString{    return @[@"?", @"A", @"2", @"3", @"4", @"5", @"6", @"7", @"8", @"9", @"10", @"J", @"Q", @"K", ][self.rank];}#define CORNER_FONT_STANDARD_HEIGHT 180.0#define CORNER_RADIUS 12.0- (CGFloat)cornerScaleFactor { return self.bounds.size.height / CORNER_FONT_STANDARD_HEIGHT; }- (CGFloat)cornerRadius { return CORNER_RADIUS * [self cornerScaleFactor]; }- (CGFloat)cornerOffset { return [self cornerRadius]  / 3.0; }- (void)drawRect:(CGRect)rect {    // Drawing code    UIBezierPath *roundRect = [UIBezierPath bezierPathWithRoundedRect:self.bounds cornerRadius:12.0];    [roundRect addClip];    [[UIColor whiteColor] setFill];    UIRectFill(self.bounds);    [[UIColor blackColor]setStroke];    [roundRect stroke];    if (self.faceUp) {        UIImage *faceImage = [UIImage imageNamed:@"2"];        if (faceImage) {            CGRect imageRect = CGRectInset(self.bounds, self.bounds.size.width * (1.0-self.faceCardScaleFactor), self.bounds.size.height * (1.0-self.faceCardScaleFactor));            [faceImage drawInRect:imageRect];        }else {            [self drawPips];        }                [self drawCorners];    }else{        [[UIImage imageNamed:@"1"]drawInRect:self.bounds];    }    }- (void)drawPips{    }- (void)drawCorners{    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];    paragraphStyle.alignment = NSTextAlignmentCenter;    UIFont *cornerFont = [UIFont preferredFontForTextStyle:UIFontTextStyleBody];    cornerFont = [cornerFont fontWithSize:cornerFont.pointSize *[self cornerScaleFactor]];    NSAttributedString *cornerText = [[NSAttributedString alloc]initWithString:[NSString stringWithFormat:@"%@\n%@", [self rankAsString], self.suit] attributes:@{NSFontAttributeName:cornerFont, NSParagraphStyleAttributeName:paragraphStyle}];    CGRect textBounds;    textBounds.origin = CGPointMake([self cornerOffset], [self cornerOffset]);    textBounds.size = [cornerText size];    [cornerText drawInRect:textBounds];        CGContextRef context = UIGraphicsGetCurrentContext();    CGContextTranslateCTM(context, self.bounds.size.width, self.bounds.size.height);    CGContextRotateCTM(context, M_PI);    [cornerText drawInRect:textBounds];}- (void)setup{    self.backgroundColor = nil;    self.opaque = NO;    self.contentMode = UIViewContentModeRedraw;}- (void)awakeFromNib{    [self setup];}- (instancetype)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {            }    return self;}@end</span>

使用举例：

<span style="font-size:18px;">@property (weak, nonatomic) IBOutlet DrawingView *myDrawingView;</span>

<span style="font-size:18px;">self.myDrawingView.suit = @"♥️";    self.myDrawingView.rank = 13;    [self.myDrawingView addGestureRecognizer:[[UIPinchGestureRecognizer alloc]initWithTarget:self.myDrawingView action:@selector(pinch:)]];</span>

<span style="font-size:18px;">- (IBAction)swip:(UISwipeGestureRecognizer *)sender {    self.myDrawingView.faceUp = !self.myDrawingView.faceUp;}</span>