iO6 Programming pushing the limits 閱讀筆記

目錄

第一部分 iOS6新內容

第二部分 從天天工具中獲取更多（介紹平常使用控件和框架的潛力）

第三部分 完成任務的正確工具（介紹不是那麼經常使用的控件和框架）

第四部分 發揮到極限（深刻理解iOS）

前言

本書不適合沒有iOS基礎和實踐經驗的讀者，更適合那些已經開發了一個app有必定經驗的讀者。着重點更多在於爲何這麼作，而不是如何實現。更多關注設計模式，如何設計，編寫ios app，選擇合適的工具來解決平常開發遇到的問題。

源碼地址

The Code | iOS 7 Programming: Pushing the limits
http://iosptl.com/code/

 

iosptl/ios7ptl · GitHub 
https://github.com/iosptl/ios7ptl

 

iOS 繪圖代碼

Chapter 8 Better Drawing

繪製直線

#import "LineView.h"

@implementation LineView


- (void)drawRect:(CGRect)rect {

    CGContextRef context=UIGraphicsGetCurrentContext();

    CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

    CGContextSetLineWidth(context, 3.0);
    // Draw 3pt horizontal line from {10,100} to {200,100}

    CGContextMoveToPoint(context, 10.0, 100.0);
    CGContextAddLineToPoint(context, 200.0, 100.0);
    CGContextStrokePath(context);


    // Draw 3pt horizontal line from {10,105.5} to {200,105.5}
    CGContextMoveToPoint(context, 10.0, 105.5);
    CGContextAddLineToPoint(context, 200.0, 105.5);
    CGContextStrokePath(context);

}


@end

vc中調用

  LineView *lineView=[[LineView alloc]initWithFrame:self.view.bounds];
  lineView.backgroundColor=[UIColor whiteColor];
  [self.view addSubview:lineView];

繪製貝賽爾曲線

#import "FlowerView.h"

@implementation FlowerView
- (void)drawRect:(CGRect)rect {
    CGSize size = self.bounds.size;
    CGFloat margin = 10;
    CGFloat radius = rint(MIN(size.height - margin,
                              size.width - margin) / 4);
    CGFloat xOffset, yOffset;
    CGFloat offset = rint((size.height - size.width) / 2);
    if (offset > 0) {
        xOffset = rint(margin / 2);
        yOffset = offset;
    }
    else {
        xOffset = -offset;
        yOffset = rint(margin / 2);
    }
    [[UIColor redColor] setFill];
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path addArcWithCenter:CGPointMake(radius * 2 + xOffset,15)
                    radius:radius
                startAngle:-M_PI
                  endAngle:0
                 clockwise:YES];

    [path addArcWithCenter:CGPointMake(radius * 3 + xOffset,
                                       radius * 2 + yOffset)
                    radius:radius
                startAngle:-M_PI_2
                  endAngle:M_PI_2
                 clockwise:YES];
    [path addArcWithCenter:CGPointMake(radius*2+xOffset,
                                       radius*3+yOffset)
                    radius:radius
                startAngle:0
                  endAngle:M_PI clockwise:YES];

    [path addArcWithCenter:CGPointMake(radius*2+xOffset,
                                       radius*3+yOffset)
                    radius:radius
                startAngle:0
                  endAngle:M_PI
                 clockwise:YES];
    [path addArcWithCenter:CGPointMake(radius + xOffset,
                                       radius * 2 + yOffset)
                    radius:radius
                startAngle:M_PI_2
                  endAngle:-M_PI_2
                 clockwise:YES];
    [path closePath];
    [path fill];

 

}

在vc中調用

  FlowerView *flowerView=[[FlowerView alloc]initWithFrame:self.view.bounds];
  
  [self.view addSubview:flowerView];

繪製股票曲線圖

效果圖以下所示

#import "GraphView.h"


@implementation GraphView {
    dispatch_source_t _timer;
}
const CGFloat kXScale = 5.0;
const CGFloat kYScale = 100.0;
static inline CGAffineTransform
CGAffineTransformMakeScaleTranslate(CGFloat sx, CGFloat sy,
                                    CGFloat dx, CGFloat dy) {
    return CGAffineTransformMake(sx, 0.f, 0.f, sy, dx, dy);
}
- (void)awakeFromNib {
    [super awakeFromNib];
    [self setContentMode:UIViewContentModeRight];
    _values = [NSMutableArray array];
    __weak id weakSelf = self;

    //設定繪圖的間隔時間
    double delayInSeconds = 0.25;
    _timer =
    dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,
                           dispatch_get_main_queue());
    dispatch_source_set_timer(
                              _timer, dispatch_walltime(NULL, 0),
                              (unsigned)(delayInSeconds * NSEC_PER_SEC), 0);
    dispatch_source_set_event_handler(_timer, ^{
        [weakSelf updateValues];
    });
    dispatch_resume(_timer);
}
- (void)updateValues {
    double nextValue = sin(CFAbsoluteTimeGetCurrent())
    + ((double)rand()/(double)RAND_MAX);
    [self.values addObject:
     [NSNumber numberWithDouble:nextValue]];
    CGSize size = self.bounds.size;
    CGFloat maxDimension = MAX(size.height, size.width);
    NSUInteger maxValues =
    (NSUInteger)floorl(maxDimension / kXScale);
    if ([self.values count] > maxValues) {
        [self.values removeObjectsInRange:
         NSMakeRange(0, [self.values count] - maxValues)];
    }
    [self setNeedsDisplay];
}

- (void)drawRect:(CGRect)rect {
    if ([self.values count] == 0) {
        return; }
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextSetStrokeColorWithColor(ctx,
                                     [[UIColor redColor] CGColor]);
    CGContextSetLineJoin(ctx, kCGLineJoinRound);
    CGContextSetLineWidth(ctx, 5);
    CGMutablePathRef path = CGPathCreateMutable();
    CGFloat yOffset = self.bounds.size.height / 2;
    CGAffineTransform transform =
    CGAffineTransformMakeScaleTranslate(kXScale, kYScale,
                                        0, yOffset);
    CGFloat y = [[self.values objectAtIndex:0] floatValue];
    CGPathMoveToPoint(path, &transform, 0, y);
    for (NSUInteger x = 1; x < [self.values count]; ++x) {
        y = [[self.values objectAtIndex:x] floatValue];
        CGPathAddLineToPoint(path, &transform, x, y);
    }
    CGContextAddPath(ctx, path);
    CGPathRelease(path);
    CGContextStrokePath(ctx);
}
@end

在vc中調用

須要建立一個xib文件和一了類，而後將xib的class設置爲GraphView

  NSArray * nib = [[NSBundle mainBundle]loadNibNamed:@"GraphView"
                                                 owner:self options:nil] ;
    GraphView *graphView= [nib lastObject];
    [self.view addSubview:graphView];

對文字進行渲染

-(UIImage *)reverseImageForText:(NSString *)text{

    const size_t kImageWidth=200;
    const size_t kImageHeight=200;
    CGImageRef textImage=NULL;
    UIFont *font=[UIFont boldSystemFontOfSize:13.0];

    UIGraphicsBeginImageContext(CGSizeMake(kImageWidth, kImageHeight));
    [[UIColor redColor]set];
    [text drawInRect:CGRectMake(0, 0, kImageWidth, kImageHeight) 
    withAttributes:@{NSFontAttributeName:font}];

    textImage=UIGraphicsGetImageFromCurrentImageContext().CGImage;
    UIGraphicsEndImageContext();

    return [UIImage imageWithCGImage:textImage scale:1.0 orientation:UIImageOrientationDownMirrored];


}

調用

    
    UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(100, 100, 200, 200)];
    imageView.image= [self reverseImageForText:@"Hello World!"];
    imageView.backgroundColor=[UIColor lightGrayColor];
    [self.view addSubview:imageView];

iOS 須要從新繪製整個視圖

setNeedsDisplay，若是隻想繪製部分視圖，能夠使用CALayer

CGLayer高效的一種繪圖

旋轉的文字效果

#import "LayerView.h"

@implementation LayerView


// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {

        static CGLayerRef sTextLayer = NULL;
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        if (sTextLayer == NULL) {
            CGRect textBounds = CGRectMake(0, 0, 200, 100);
            sTextLayer = CGLayerCreateWithContext(ctx,
                                                  textBounds.size,
                                                  NULL);
            CGContextRef textCtx = CGLayerGetContext(sTextLayer);
            CGContextSetRGBFillColor (textCtx, 1.0, 0.0, 0.0, 1);
            UIGraphicsPushContext(textCtx);
            UIFont *font = [UIFont systemFontOfSize:13.0];
            [@"Pushing The Limits" drawInRect:textBounds withFont:font];
            UIGraphicsPopContext();
        }

            CGContextTranslateCTM(ctx, self.bounds.size.width / 2,
                                  self.bounds.size.height / 2);
            for (NSUInteger i = 0; i < 10; ++i) {
                CGContextRotateCTM(ctx, 2 * M_PI / 10);
                CGContextDrawLayerAtPoint(ctx,
                                          CGPointZero,
                                          sTextLayer);
            }

}


@end

調用代碼

   LayerView *layerView=[[LayerView alloc]initWithFrame:self.view.bounds];
    layerView.backgroundColor=[UIColor whiteColor];

    [self.view addSubview:layerView];

效果圖

UIView animation

frame位移的動畫

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic,strong) UIView *circleView;

@end

@implementation ViewController


- (void)viewDidLoad {
    [super viewDidLoad];
    self.circleView = [[UIView alloc] initWithFrame:
                       CGRectMake(100, 100, 20, 20)];
    self.circleView.center = CGPointMake(100, 20);
    self.circleView.backgroundColor=[UIColor redColor];
    [[self view] addSubview:self.circleView];
    UITapGestureRecognizer *g;
    g = [[UITapGestureRecognizer alloc]
         initWithTarget:self
         action:@selector(dropAnimate)];
    [[self view] addGestureRecognizer:g];
}

- (void)dropAnimate {
    [UIView animateWithDuration:3 animations:^{
        self.circleView.center = CGPointMake(100, 300);
    }];
}

UIView animation只提供基本的動畫功能，不支持3d，更多效果須要使用core animation的CALayer

CALayer只負責繪圖，不處理用戶事件

 

 

tableview的內容

下拉刷新和上拉加載更多

下拉刷新能夠用UIRefreshControl

 

上拉加載更多能夠本身封裝一個tableview的superClass在最後加上section，顯示加載更多的內容

 

鍵盤遮擋的一種解決方法

經過接收鍵盤出現的通知，將tableview的高度減去鍵盤的高度。接收鍵盤消失的通知，加上鍵盤的高度，這樣就OK。