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iOS开发零碎知识点

yaoqiyaoqi

本篇文章记录了iOS开发零碎知识点，简单又实用！

代码写了这么多，但是总是有些知识点在真正需要用到的时候却遗忘了，一直想整理这块知识，最近又总是在赶项目，不管再忙，这块总是要整理起来。

iOS开发零碎知识点

修改Cell分割线距离

修改UITableviewCell的分割线距离通常需要修改separatorInset属性的top, left, bottom, right：

 
- (void)tableView:(UITableView *)tableViewwillDisplayCell:(UITableViewCell *)cellforRowAtIndexPath:(NSIndexPath *)indexPath {
    if ([cellrespondsToSelector:@selector(setSeparatorInset:)]) {
        [cellsetSeparatorInset:UIEdgeInsetsMake(0, 15, 0, 15)];
    }
    if ([cellrespondsToSelector:@selector(setLayoutMargins:)]) {
        [cellsetSeparatorInset:UIEdgeInsetsMake(0, 15, 0, 15)];
    }
    if ([cellrespondsToSelector:@selector(setPreservesSuperviewLayoutMargins:)]) {
        [cellsetPreservesSuperviewLayoutMargins:NO];
    }
}

去掉Cell的分割线

 
myTableView.separatorStyle = UITableViewCellSeparatorStyleNone;

取消Cell的选中效果

 
myTableView.selectionStyle = UITableViewCellSelectionStyleNone;

视图过大不响应

子视图超出父视图，子视图点击事件不响应。一般子视图超出父视图，子视图点击等事件是不响应的，因为事件的传递链不会传到超出父视图的视图上面，需要我们用 hitTest:withEvent: 处理下。

 
- (UIView *)hitTest:(CGPoint)pointwithEvent:(UIEvent *)event {
    CGPoint hitPoint = [self.cardView.dayRateHelpconvertPoint:pointfromView:self];
    if ([self.cardView.dayRateHelppointInside:hitPointwithEvent:event])
        return self.cardView.dayRateHelp;
    return [superhitTest:pointwithEvent:event];
}

注意：如果父视图是UIScrollView，需要设置 self.bgScrollView.clipsToBounds = NO; ，因为 UIScrollView 默认会进行裁剪，会导致超出的部分没有了。

修改holder

修改UITextField的Placeholder的文字颜色和大小。这里我们使用kvc设置UITextField的私有属性。

 
[textFieldsetValue:placeholderLabelTextColorforKeyPath:@"_placeholderLabel.textColor"];
[textFieldsetValue:[UIFontsystemFontOfSize:placeholderLabelFont]forKeyPath:@"_placeholderLabel.font"];

修改UIPageControl图片

修改UIPageControl的选中图片和默认图片。默认也是不允许修改的，需要用到kvc设置。

 
[self.pageControlsetValue:currentImageforKey:@"_currentPageImage"];
[self.pageControlsetValue:pageImageforKey:@"_pageImage"];

修改系统相机拍照功能

1、将使用照片改成保存至相册；

2、监听拍照按钮点击事件；

3、监听重拍按钮点击事件；

4、在拍照里面添加自定义view放到cameraOverlayView上。

 
- (void)navigationController:(UINavigationController *)navigationControllerdidShowViewController:(UIViewController *)viewControlleranimated:(BOOL)animated {
    [selfaddSomeElements:viewController];
}
    
- (UIView *)findView:(UIView *)aViewwithName:(NSString *)name {
    Class cl = [aViewclass];
    NSString *desc = [cldescription];
    if ([nameisEqualToString:desc]) return aView;
    for (UIView *view in aView.subviews) {
        Class cll = [viewclass];
        NSString *stringl = [clldescription];
        if ([stringlisEqualToString:name]) {
            return view;
        }
    }
    return nil;
}
 
- (void)addSomeElements:(UIViewController *)viewController {
    UIView *PLCropOverlay = [selffindView:viewController.viewwithName:@"PLCropOverlay"];
    UIView *PLCropOverlayBottomBar = [selffindView:PLCropOverlaywithName:@"PLCropOverlayBottomBar"];
    UIView *PLCropOverlayPreviewBottomBar = [selffindView:PLCropOverlayBottomBarwithName:@"PLCropOverlayPreviewBottomBar"];
    UIButton *userButton = [PLCropOverlayPreviewBottomBar.subviewsobjectAtIndex:2];
 
    UIButton *viewbtn = [[UIButton alloc]init];
    [viewbtnsetTitle:@"保存至相册"forState:UIControlStateNormal];
    [viewbtnsetTitleColor:[UIColor whiteColor]forState:0];
    viewbtn.backgroundColor = RGB(19, 20, 21);
    [userButtonaddSubview:viewbtn];
    [viewbtnmas_makeConstraints:^(MASConstraintMaker *make) {
        make.trailing.equalTo(userButton.mas_trailing);
        make.centerY.equalTo(userButton);
    }];
    viewbtn.userInteractionEnabled = NO;
 
    //给拍照加点击事件
    UIView *CMKBottomBar = [selffindView:viewController.viewwithName:@"CMKBottomBar"];
    UIButton *CMKShutterButton = (UIButton *) [selffindView:CMKBottomBarwithName:@"CMKShutterButton"];
    [CMKShutterButtonaddTarget:selfaction:@selector(shutterButtonClicked)forControlEvents:UIControlEventTouchUpInside];
 
    //监听重拍
    UIButton *resetButton = [PLCropOverlayPreviewBottomBar.subviewsobjectAtIndex:0];
    [resetButtonaddTarget:selfaction:@selector(resetButtonClicked)forControlEvents:UIControlEventTouchUpInside];
}

注意：viewbtn.userInteractionEnabled = NO;的作用是防止这层视图的点击事件影响系统的使用照片按钮的点击事件；在这里给拍照按钮和重拍按钮添加了点击事件，既满足了自己需要做的事情，又不影响系统对这两个按钮的点击事件。