iOS Develop Tips

Speed123
312 阅读6分钟

前言

记录一些代码小技巧持续更新😜!

Objective-C tips

1、使控件从导航栏以下开始

 self.edgesForExtendedLayout=UIRectEdgeNone;

2、将navigation返回按钮文字position设置不在屏幕上显示

[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(NSIntegerMin, NSIntegerMin) forBarMetrics:UIBarMetricsDefault];

3、解决ScrollView等在viewController无法滚动到最顶部

//自动滚动调整，默认为YES
self.automaticallyAdjustsScrollViewInsets = NO;

4、隐藏navigationBar上返回按钮

[self.navigationController.navigationItem setHidesBackButton:YES];
[self.navigationItem setHidesBackButton:YES];
[self.navigationController.navigationBar.backItem setHidesBackButton:YES];

5、当tableView占不满一屏时，去除上下边多余的单元格

self.tableView.tableHeaderView = [UIView new];
self.tableView.tableFooterView = [UIView new];

6、显示完整的CellSeparator线

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath{
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
        [cell setSeparatorInset:UIEdgeInsetsZero];
    }
    if ([cell respondsToSelector:@selector(setPreservesSuperviewLayoutMargins:)]) {
        [cell setPreservesSuperviewLayoutMargins:NO];
    }
    if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
        [cell setLayoutMargins:UIEdgeInsetsZero];
    }
}

7、滑动的时候隐藏navigation bar

navigationController.hidesBarsOnSwipe = Yes;

8、将Navigationbar变成透明而不模糊

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

9、NSString常用处理方法

//截取字符串
NSString *interceptStr1 = @"Tate_zwt";
interceptStr1 = [interceptStr1 substringToIndex:3];//截取下标3之前的字符串
NSLog(@"截取的值为:%@",interceptStr1);//截取的值为:Tat

NSString *interceptStr2 = @"Tate_zwt";
NSRange rang = {3,1};
interceptStr2 = [interceptStr2 substringWithRange:rang];//截取rang范围的字符串
NSLog(@"截取的值为:%@",interceptStr2);//截取的值为:e

NSString *interceptStr3 = @"Tate_zwt";
interceptStr3 = [interceptStr3 substringFromIndex:3];//截取下标3之后的字符串
NSLog(@"截取的值为:%@",interceptStr3);//截取的值为:e_zwt


//匹配字符串
NSString *matchingStr = @"Tate_zwt";
NSRange range = [matchingStr rangeOfString:@"t"];//匹配得到的下标
NSLog(@"rang:%@",NSStringFromRange(range));//rang:{2, 1}
matchingStr = [matchingStr substringWithRange:range];//截取范围类的字符串
NSLog(@"截取的值为:%@",matchingStr);//截取的值为:t


//分割字符串
NSString *splitStr = @"Tate_zwt_zwt";
NSArray *array = [splitStr componentsSeparatedByString:@"_"]; //从字符A中分隔成2个元素的数组
NSLog(@"array:%@",array); //输出3个对象分别是:Tate,zwt,zwt


//拼接字符串
NSMutableString *appendStr =  [NSMutableString string];
//使用逗号拼接
//[append appendFormat:@"%@zwt", append.length ? @"," : @""];
[appendStr appendString:@"我是"];
[appendStr appendString:@"Tate-zwt"];
NSLog(@"%@",appendStr);//输出:我是Tate-zwt


//替换字符串
NSString *replaceStr = @"我是&nbspTate-zwt";
replaceStr = [replaceStr stringByReplacingOccurrencesOfString:@"&nbsp" withString:@""];
NSLog(@"%@",replaceStr);//输出:我是Tate-zwt
        
        
//判断字符串内是否还包含特定的字符串(前缀，后缀)
NSString *hasStr = @"Tate.zwt";
[hasStr hasPrefix:@"Tate"] == 1 ?  NSLog(@"YES") : NSLog(@"NO"); //前缀
[hasStr hasSuffix:@".zwt"] == 1 ?  NSLog(@"YES") : NSLog(@"NO"); // 后缀


//字符串是否包含特定的字符
NSString *containStr = @"iOS Developer,喜欢做有趣的产品";
NSRange rangeDeveloper = [containStr rangeOfString:@"Developer"];
NSRange rangeProduct = [containStr rangeOfString:@"Product"];
rangeDeveloper.location != NSNotFound == 1 ?  NSLog(@"YES") : NSLog(@"NO");
rangeProduct.location != NSNotFound == 1 ?  NSLog(@"YES") : NSLog(@"NO");

10、UIPageControl如何改变点的大小? 重写setCurrentPage方法即可:

- (void)setCurrentPage:(NSInteger)page {
    [super setCurrentPage:page];
    for (NSUInteger subviewIndex = 0; subviewIndex < [self.subviews count]; subviewIndex++) {
        UIView *subview = [self.subviews objectAtIndex:subviewIndex];
        UIImageView *imageView = nil;
        if (subviewIndex == page) {
            CGFloat w = 8;
            CGFloat h = 8;
            imageView = [[UIImageView alloc] initWithFrame:CGRectMake(-1.5, -1.5, w, h)];
            imageView.image = [UIImage imageNamed:@"banner_red"];
            [subview setFrame:CGRectMake(subview.frame.origin.x, subview.frame.origin.y, w, h)];
        } else {
            CGFloat w = 5;
            CGFloat h = 5;
            imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, w, h)];
            imageView.image = [UIImage imageNamed:@"banner_gray"];
            [subview setFrame:CGRectMake(subview.frame.origin.x, subview.frame.origin.y, w, h)];
        }
        imageView.tag = 10010;
        UIImageView *lastImageView = (UIImageView *) [subview viewWithTag:10010];
        [lastImageView removeFromSuperview]; //把上一次添加的view移除
        [subview addSubview:imageView];
    }
}

11、如何改变多行UILabel的行高？ Show me the code：

    _promptLabel = [UILabel new];
    NSString *labelText = @"Talk is cheap\nShow me the code";
    _promptLabel.text = labelText;
    _promptLabel.numberOfLines = 2;
    _promptLabel.font = [UIFont systemFontOfSize:14];
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:labelText];
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    [paragraphStyle setLineSpacing:10]; //调整行间距
    [attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [labelText length])];
    _promptLabel.attributedText = attributedString;
    [_promptLabel sizeToFit];
    [self.view addSubview:_promptLabel];

12、如何让Label等控件支持HTML格式的代码？ 使用NSAttributedString:

NSString *htmlString = @"<div>Tate<span style='color:#1C86EE;'>《iOS Develop Tips》</span>get <span style='color:#1C86EE;'>Tate_zwt</span> 打赏 <span style='color:#FF3E96;'>100</span> 金币</div>";
NSAttributedString *attributedString = [[NSAttributedString alloc] initWithData:[htmlString dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType } documentAttributes:nil error:nil];
_contentLabel.attributedText = attributedString;

13、如何让Label等控件同时支持HTML代码和行间距？

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithData:[_open_bonus_article dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType } documentAttributes:nil error:nil];
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[paragraphStyle setLineSpacing:12]; //调整行间距
[attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [attributedString length])];
_detailLabel.attributedText = attributedString;
[_detailLabel sizeToFit];

14、pop回根控制器视图

//这里也可以指定pop到哪个索引控制器
[self.navigationController popToViewController: [self.navigationController.viewControllers objectAtIndex: ([self.navigationController.viewControllers count] - 3)] animated:YES];
//或者
[self.navigationController popToRootViewControllerAnimated:YES];

15、dismiss回根控制器视图(PS：只能返回两层)

if ([self respondsToSelector:@selector(presentingViewController)]){
self.presentingViewController.view.alpha = 0;
[self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:nil];
 }else {
self.parentViewController.view.alpha = 0;
[self.parentViewController.parentViewController dismissViewControllerAnimated:YES completion:nil];
 }
//或者
if ([self respondsToSelector:@selector(presentingViewController)]){
[self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:nil];
}else {
[self.parentViewController.parentViewController dismissViewControllerAnimated:YES completion:nil];
}

16、两个控制器怎么无限push?

NSMutableArray *vcArr = [self.navigationController.viewControllers mutableCopy];
[vcArr removeLastObject];
[vcArr addObject:loginVC];
[self.navigationController setViewControllers:vcArr animated:YES];

17、NSDictionary 怎么转成NSString

NSData *jsonData = [NSJSONSerialization dataWithJSONObject:response.data options:0 error:0];
NSString *dataStr =  [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

18、获取系统可用存储空间 ，单位：字节

/**
 *  获取系统可用存储空间
 *
 *  @return 系统空用存储空间，单位：字节
 */
-(NSUInteger)systemFreeSpace{
    NSString *docPath=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSDictionary *dict=[[NSFileManager defaultManager] attributesOfFileSystemForPath:docPath error:nil];
    return [[dict objectForKey:NSFileSystemFreeSize] integerValue];
}

19、有时OC调用JS代码没反应？ stringByEvaluatingJavaScriptFromString 必须在主线程里执行

dispatch_async(dispatch_get_main_queue(), ^{
            [weakSelf.webView stringByEvaluatingJavaScriptFromString:jsStr];
//            [weakSelf.webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"alertTest('%@');", @"test"]];
        });

20、获取相册图片的名称及后缀

#pragma mark UIImagePickerControllerDelegate
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
//获取图片的名字
     __block NSString* fileName;
    NSURL *imageURL = [info valueForKey:UIImagePickerControllerReferenceURL];
    ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
    {
        ALAssetRepresentation *representation = [myasset defaultRepresentation];
        fileName = [representation filename];
        NSLog(@"fileName : %@",fileName);
        self.imageFileName = fileName;
    };
    
    ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
    [assetslibrary assetForURL:imageURL
                   resultBlock:resultblock
                  failureBlock:nil];
}

21、UITableView 自动滑动到某一行

//四种枚举样式
UITableViewScrollPositionNone,
UITableViewScrollPositionTop,
UITableViewScrollPositionMiddle,
UITableViewScrollPositionBottom

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
//第一种方法
[tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionTop animated:YES];
//第二种方法
[self.tableVieW selectRowAtIndexPath:indexPath animated:YES scrollPosition:UITableViewScrollPositionTop];

22、 Xcode8注释快捷键不能使用的解决方法： In Terminal: sudo /usr/libexec/xpccachectl

最近使用CocoaPods来添加第三方类库，无论是执行pod install还是pod update都卡在了Analyzing dependencies不动 原因在于当执行以上两个命令的时候会升级CocoaPods的spec仓库，加一个参数可以省略这一步，然后速度就会提升不少。加参数的命令如下：

pod install --verbose --no-repo-update
pod update --verbose --no-repo-update

你可以 cd ~/.cocoapods/repos/ 到这个目录下 执行du -sh * 看下下载了多少

23、获取模拟器沙盒路径

NSArray *aryPath=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
//沙盒路劲
NSString *strDocPath=[aryPath objectAtIndex:0];

24、tableView.tableHeaderView 一些设置方法

    _tableView.tableHeaderView = _heatOrTimeView;
    [_heatOrTimeView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.right.top.equalTo(_tableView);
        make.width.equalTo(_tableView);
        make.height.mas_equalTo(@36);
    }];
//    如果是动态改变高度的话这里要加上以下代码
//    [_tableView layoutIfNeeded];
//    [_tableView beginUpdates]; 这个是增加动画效果
//    [_tableView endUpdates];
//    _tableView.tableHeaderView = _heatOrTimeView;

25、约束如何做UIView动画？

1、把需要改的约束Constraint拖条线出来，成为属性
2、在需要动画的地方加入代码，改变此属性的constant属性
3、开始做UIView动画，动画里边调用layoutIfNeeded方法

@property (weak, nonatomic) IBOutlet NSLayoutConstraint *buttonTopConstraint;
self.buttonTopConstraint.constant = 100;
    [UIView animateWithDuration:.5 animations:^{
        [self.view layoutIfNeeded];
    }];

26、删除某个view所有的子视图

[[someView subviews] makeObjectsPerformSelector:@selector(removeFromSuperview)];

27、将一个view放置在其兄弟视图的最上面

[parentView bringSubviewToFront:yourView]

28、将一个view放置在其兄弟视图的最下面

[parentView sendSubviewToBack:yourView]

29、layoutSubviews方法什么时候调用？

1、init方法不会调用
2、addSubview方法等时候会调用
3、bounds改变的时候调用
4、scrollView滚动的时候会调用scrollView的layoutSubviews方法(所以不建议在scrollView的layoutSubviews方法中做复杂逻辑)
5、旋转设备的时候调用
6、子视图被移除的时候调用参考请看：[http://blog.logichigh.com/2011/03/16/when-does-layoutsubviews-get-called/](http://blog.logichigh.com/2011/03/16/when-does-layoutsubviews-get-called/)

30、isKindOfClass和isMemberOfClass的区别

isKindOfClass可以判断某个对象是否属于某个类，或者这个类的子类。
isMemberOfClass更加精准，它只能判断这个对象类型是否为这个类(不能判断子类)

31、IOS App开启iTunes文件共享（文稿）

通过在app工程的Info.plist文件中指定Application supports iTunes file sharing关键字，并将其值设置为YES。
我们可以很方便的打开app与iTunes之间的文件共享。
但这种共享有一个前提：App必须将任何所需要共享给用户的文件，都要存放在<Application_Home>/Documents目录下，<Application_Home>即在app安装时自动创建的app的主目录。

32、去掉UITabBar的分割线的方法

[[UITabBar appearance] setShadowImage:[UIImage new]];
[[UITabBar appearance] setBackgroundImage:[UIImage new]];
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