iOS编程常用方法和常见bug修复

1.去除NSString字符串里面的特殊符号

-(NSString*)deleteSpecificSymbolForString:(NSString*)text{
    //先创建NSCharacterSet，把需要去除的字符串放在里面
    NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@"@／:：；;¥「」＂、[]{}#%-*+=_\\|~＜＞$€^•'@#$%^&*()（）_+'\""];
    //该方法返回的就是去除特殊符号后的字符串
    NSString *trimmedString = [text stringByTrimmingCharactersInSet:set];
    return trimmedString;
}

2.判断NSString字符串里面有没有汉字

-(BOOL)estimateStringContainChinese:(NSString*)text{
    if(text){
        for (int i=0; i

3.判断NSString字符串里面有没有英文字母

-(BOOL)estimateStringContainEnglish:(NSString*)text{
    if(text){
        for (int i=0; i

4.在指定控制器里面更改状态栏文字颜色

  每一个应用程序，应该都会有统一的导航栏和状态栏风格。但是有时候，也有需要在指定控制器里面修改
状态栏的风格，如：播放视频。
-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleDefault animated:YES];
}

-(void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent animated:YES];
}

5.点击进入搜索控制器时，自动弹出键盘，让搜索框进入编辑状态

当点击搜索时，进入搜索控制器，使用系统自带的搜索框，searchController.searchBar，进入时，自动实现如下图的效果

效果图.png

找了很多方法，下面这个是有效方法：

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    [self performSelector:@selector(showKeyboard) withObject:nil afterDelay:0];
}

- (void)showKeyboard {
    [self.searchController.searchBar becomeFirstResponder];
}

6.修改系统自带搜索框的UI

  系统自带的搜索框，使用方便快捷，但是有时候它的外观与要求不符，这时候就需要我们来对系统搜索框
进行一些修改
for (UIView* subview in [[self.searchController.searchBar.subviews lastObject] subviews]) {
        //相当于UITextField，输入框，可以修改背景颜色等
        if ([subview isKindOfClass:NSClassFromString(@"UISearchBarTextField")]) {
            UITextField *textField = (UITextField*)subview;
            [textField setBackgroundColor:COLOR_RGB(238, 238, 238)];
        }
        //相当于UIButton，搜索框右侧的Cancle按钮，可以修改默认文字等
        if ([subview isKindOfClass:NSClassFromString(@"UINavigationButton")]) {
            UIButton* cancle = (UIButton*)subview;
            [cancle setTitle:@"取消" forState:UIControlStateNormal];
            [cancle setTitleColor:COLOR_RGB(82, 184, 255) forState:UIControlStateNormal];
        }
        //相当于UIView，搜索框的背景view，一般将它去掉，然后自己添加一层背景view
        if ([subview isKindOfClass:NSClassFromString(@"UISearchBarBackground")]) {
            [subview removeFromSuperview];
            UIView* back = [[UIView alloc]initWithFrame:self.searchController.searchBar.bounds];
            back .backgroundColor = [UIColor whiteColor];
            [self.searchController.searchBar insertSubview:back atIndex:0];
        }
    }

7.在指定控制器中隐藏导航栏

  有时候，需要在指定控制器中隐藏导航栏，试过好几个方法，或多或少有些坑，下面这个是我认为比较好的：
  首先让该控制器成为导航栏的代理：
  self.navigationController.delegate = self;
  然后，实现指定的代理方法：
  -(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated{
    if ([viewController isKindOfClass:[self class]]) {
        [self.navigationController setNavigationBarHidden:YES animated:YES];
    }
    //返回时，在指定控制器重新让导航栏显示
    if ([viewController isKindOfClass:[ContactVC class]]) {
        [self.navigationController setNavigationBarHidden:NO animated:YES];
    }
}

8.根据指定文本，字体，固定宽度或高度，求尺寸

// 根据指定文本,字体和最大高度计算尺寸
- (CGSize)sizeWithText:(NSString *)text font:(UIFont *)font maxHeight:(CGFloat)height
{
    NSMutableDictionary *attrDict = [NSMutableDictionary dictionary];
    attrDict[NSFontAttributeName] = font;
    CGSize size = [text boundingRectWithSize:CGSizeMake(MAXFLOAT, height) options:NSStringDrawingUsesLineFragmentOrigin attributes:attrDict context:nil].size;
    return size;
}
// 根据指定文本,字体和最大宽度计算尺寸
- (CGSize)sizeWithText:(NSString *)text font:(UIFont *)font maxWidth:(CGFloat)width
{
    NSMutableDictionary *attrDict = [NSMutableDictionary dictionary];
    attrDict[NSFontAttributeName] = font;
    CGSize size = [text boundingRectWithSize:CGSizeMake(width, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:attrDict context:nil].size;
    return size;
}

9.给UILabel设置行间距，字间距等富文本属性，并计算高度

//给UILabel设置行间距和字间距
-(void)setLabelSpace:(UILabel*)label withValue:(NSString*)str withFont:(UIFont*)font {
    NSMutableParagraphStyle *paraStyle = [[NSMutableParagraphStyle alloc] init];
    paraStyle.lineBreakMode = NSLineBreakByCharWrapping; //结尾部分的文字省略方式
    paraStyle.alignment = NSTextAlignmentLeft; //文本对齐方式
    paraStyle.lineSpacing = 7; //设置行间距
    paraStyle.hyphenationFactor = 1.0; //连字属性 在iOS，唯一支持的值分别为0和1
    paraStyle.firstLineHeadIndent = 0.0; //首行缩进
    paraStyle.paragraphSpacingBefore = 0.0; //段首行空白空间
    paraStyle.headIndent = 0; //整体缩进(首行除外)
    paraStyle.paragraphSpacing = 15; //段与段之间的间距
    
    //设置字间距 NSKernAttributeName:@1.5f
    NSDictionary *dic = @{NSFontAttributeName:font, NSParagraphStyleAttributeName:paraStyle, NSKernAttributeName:@1.5f};
    NSAttributedString *attributeStr = [[NSAttributedString alloc] initWithString:str attributes:dic];
    label.attributedText = attributeStr;
}

//计算UILabel的高度(带有行间距的情况)
-(CGFloat)getSpaceLabelHeight:(NSString*)str withFont:(UIFont*)font withWidth:(CGFloat)width {
    NSMutableParagraphStyle *paraStyle = [[NSMutableParagraphStyle alloc] init];
    paraStyle.lineBreakMode = NSLineBreakByCharWrapping;
    paraStyle.alignment = NSTextAlignmentLeft;
    paraStyle.lineSpacing = 7;
    paraStyle.hyphenationFactor = 1.0;
    paraStyle.firstLineHeadIndent = 0.0;
    paraStyle.paragraphSpacingBefore = 0.0;
    paraStyle.headIndent = 0;
    paraStyle.paragraphSpacing = 15;
    
    NSDictionary *dic = @{NSFontAttributeName:font, NSParagraphStyleAttributeName:paraStyle, NSKernAttributeName:@1.5f};
    CGSize size = [str boundingRectWithSize:CGSizeMake(width, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:dic context:nil].size;
    
    return size.height;
}