iOS开发的一些奇巧淫技2

来源：互联网发布：做施工组织设计的软件编辑：程序博客网时间：2024/05/21 05:06

本文整理了一些iOS开发中常见和不常见的技巧，是大受欢迎的iOS开发的一些奇巧淫技第二篇，技术的提高就在这些细节当中~

能不能只用一个pan手势来代替UISwipegesture的各个方向?

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- (void)pan:(UIPanGestureRecognizer *)sender
{
 
typedef NS_ENUM(NSUInteger, UIPanGestureRecognizerDirection) {
    UIPanGestureRecognizerDirectionUndefined,
    UIPanGestureRecognizerDirectionUp,
    UIPanGestureRecognizerDirectionDown,
    UIPanGestureRecognizerDirectionLeft,
    UIPanGestureRecognizerDirectionRight
};
 
static UIPanGestureRecognizerDirection direction = UIPanGestureRecognizerDirectionUndefined;
 
switch (sender.state) {
 
    case UIGestureRecognizerStateBegan: {
 
        if (direction == UIPanGestureRecognizerDirectionUndefined) {
 
            CGPoint velocity = [sender velocityInView:recognizer.view];
 
            BOOL isVerticalGesture = fabs(velocity.y) > fabs(velocity.x);
 
            if (isVerticalGesture) {
                if (velocity.y > 0) {
                    direction = UIPanGestureRecognizerDirectionDown;
                } else {
                    direction = UIPanGestureRecognizerDirectionUp;
                }
            }
 
            else {
                if (velocity.x > 0) {
                    direction = UIPanGestureRecognizerDirectionRight;
                } else {
                    direction = UIPanGestureRecognizerDirectionLeft;
                }
            }
        }
 
        break;
    }
 
    case UIGestureRecognizerStateChanged: {
        switch (direction) {
            case UIPanGestureRecognizerDirectionUp: {
                [self handleUpwardsGesture:sender];
                break;
            }
            case UIPanGestureRecognizerDirectionDown: {
                [self handleDownwardsGesture:sender];
                break;
            }
            case UIPanGestureRecognizerDirectionLeft: {
                [self handleLeftGesture:sender];
                break;
            }
            case UIPanGestureRecognizerDirectionRight: {
                [self handleRightGesture:sender];
                break;
            }
            default: {
                break;
            }
        }
        break;
    }
 
    case UIGestureRecognizerStateEnded: {
        direction = UIPanGestureRecognizerDirectionUndefined;   
        break;
    }
 
    default:
        break;
}
 
}

拉伸图片的时候怎么才能让图片不变形？

1. UIImage *image = [[UIImage imageNamed:@"xxx"] stretchableImageWithLeftCapWidth:10 topCapHeight:10];
(刚才有人提醒这个已经deprecated了哈,现在的方法叫resizableImageWithCapInsets).

2.如下操作：

怎么播放GIF的时候这么卡，有没有好点的库？

FlipBoard出品的太适合你了。https://github.com/Flipboard/FLAnimatedImage

怎么一句话添加上拉刷新？

https://github.com/samvermette/SVPullToRefresh

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[tableView addPullToRefreshWithActionHandler:^{
// prepend data to dataSource, insert cells at top of table view
// call [tableView.pullToRefreshView stopAnimating] when done
} position:SVPullToRefreshPositionBottom];

怎么把tableview里cell的小对勾的颜色改成别的颜色？

_mTableView.tintColor = [UIColor redColor];

本来我的statusbar是lightcontent的，结果用UIImagePickerController会导致我的statusbar的样式变成黑色，怎么办？

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- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated { 
    [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent]; 
}

怎么把我的navigationbar弄成透明的而不是带模糊的效果？

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[self.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault]; self.navigationBar.shadowImage = [UIImage new]; 
self.navigationBar.translucent = YES;

怎么改变uitextfield placeholder的颜色和位置？

继承uitextfield，重写这个方法

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- (void) drawPlaceholderInRect:(CGRect)rect { 
    [[UIColor blueColor] setFill]; 
    [self.placeholder drawInRect:rect withFont:self.font lineBreakMode:UILineBreakModeTailTruncation alignment:self.textAlignment]; 
}

你为什么知道这么多奇怪的花招？

去stackoverflow刷问题啊，少年！
（本文作者：叶孤城___）

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