iOS 常用知识总结

• 1.隐藏导航栏上的返回字体

//Swift
UIBarButtonItem.appearance().setBackButtonTitlePositionAdjustment(UIOffsetMake(0, -60), forBarMetrics: .Default)
//OC
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];

• 2.去掉tableView多余的线条

//Swift
self.tableView?.tableFooterView = UIView()
//OC
self.tableView.tableFooterView = [UIView new];

• 3.去掉tableView的线条

//Swift
self.tableView?.separatorStyle = .None
//OC
 self.tableView.separatorStyle = UITableViewCellSeparatorStyleNone;

• 4.去掉cell的选中效果

//Swift
cell.selectionStyle = .None
//OC
cell.selectionStyle = UITableViewCellSelectionStyleNone;

• 5.解决tableview的分割线短一截

-(void)viewDidLayoutSubviews

{
    if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {
        [self.tableView setSeparatorInset:UIEdgeInsetsMake(0,0,0,0)];
    }

    if ([self.tableView respondsToSelector:@selector(setLayoutMargins:)]) {
        [self.tableView setLayoutMargins:UIEdgeInsetsMake(0,0,0,0)];
    }
}

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
        [cell setSeparatorInset:UIEdgeInsetsZero];
    }

    if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
        [cell setLayoutMargins:UIEdgeInsetsZero];
    }
}

• 6.在swift中定义协议的时候,如果使用如下方法定义,需要在声明时,使用weak来修饰以防止循环引用

@objc protocol BookTabBarDelegate{
    func commet()
    func commetnController()
    func likeBook()
    func shareAction()
}
weak var delegate:BookTabBarDelegate?

• 7.如果使用swift语法声明一个协议时,不用使用weak进行修饰,否则会报错

protocol BookTabBarDelegate{
    func commet()
    func commetnController()
    func likeBook()
    func shareAction()
}
var delegate:BookTabBarDelegate?

• 8.动态隐藏NavigationBar

//1.当我们的手离开屏幕时候隐藏
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset{
    NSLog(@"======== %lf", velocity.y);
    if(velocity.y > 0) {
        [self.navigationController setNavigationBarHidden:YES animated:YES];
    }
    else {
        [self.navigationController setNavigationBarHidden:NO animated:YES];
    }
}
velocity.y这个量，在上滑和下滑时，变化极小（小数），但是因为方向不同，有正负之分，这就很好处理了。

效果图:

//2.在滑动过程中隐藏
//像safari
(1) self.navigationController.hidesBarsOnSwipe = YES;
(2)- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat offsetY = scrollView.contentOffset.y + _familyTableView.contentInset.top;//注意
    CGFloat panTranslationY = [scrollView.panGestureRecognizer translationInView:self.familyTableView].y;

    if (offsetY > 64) {
        if (panTranslationY > 0) { //下滑趋势，显示
            [self.navigationController setNavigationBarHidden:NO animated:YES];
        }
        else {  //上滑趋势，隐藏
            [self.navigationController setNavigationBarHidden:YES animated:YES];
        }
    }
    else {
        [self.navigationController setNavigationBarHidden:NO animated:YES];
    }
}

这里的offsetY > 64只是为了在视图滑过navigationBar的高度之后才开始处理，防止影响展示效果。
panTranslationY是scrollView的pan手势的手指位置的y值，可能不是太好，因为panTranslationY这个值在较小幅度上下滑动时，可能都为正或都为负，这就使得这一方式不太灵敏.

效果图:

• 9.设置导航栏透明

//方法一:设置透明度
  [[[self.navigationController.navigationBar subviews]objectAtIndex:0] setAlpha:0.1];
//方法二:设置背景图片
/**
 *  设置导航栏,使其透明
 *
*/
- (void)setNavigationBarColor:(UIColor *)color targetController:(UIViewController *)targetViewController
{

  //导航条的颜色 以及隐藏导航条的颜色
targetViewController.navigationController.navigationBar.shadowImage = [[UIImage alloc]init];
    CGRect rect=CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    [targetViewController.navigationController.navigationBar setBackgroundImage:theImage forBarMetrics:UIBarMetricsDefault];
}

• 10.设置字体和行间距

//设置字体和行间距
    UILabel  * lable = [[UILabel alloc]initWithFrame:CGRectMake(50, 100, 300, 200)];
    lable.text = @"大家好,我是Frank_chun,在这里我们一起学习新的知识,总结我们遇到的那些坑,共同的学习,共同的进步,共同的努力,只为美好的明天!!!有问题一起相互的探讨--438637472!!!";
    lable.numberOfLines = 0;
    lable.font = [UIFont systemFontOfSize:12];
    lable.backgroundColor = [UIColor grayColor];
    [self.view addSubview:lable];


    //设置每个字体之间的间距
    //NSKernAttributeName 这个对象所对应的值是一个NSNumber对象(包含小数),作用是修改默认字体之间的距离调整,值为0的话表示字距调整是禁用的;
    NSMutableAttributedString * str = [[NSMutableAttributedString alloc]initWithString:lable.text attributes:@{NSKernAttributeName:@(5.0)}];

    //设置某写字体的颜色
    //NSForegroundColorAttributeName 设置字体颜色
    NSRange blueRange = NSMakeRange([[str string] rangeOfString:@"Frank_chun"].location, [[str string] rangeOfString:@"Frank_chun"].length);
    [str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:blueRange];

    NSRange blueRange1 = NSMakeRange([[str string] rangeOfString:@"438637472"].location, [[str string] rangeOfString:@"438637472"].length);
    [str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:blueRange1];

    //设置每行之间的间距
    //NSParagraphStyleAttributeName 设置段落的样式
    NSMutableParagraphStyle * par = [[NSMutableParagraphStyle alloc]init];
    [par setLineSpacing:20];
    //为某一范围内文字添加某个属性
    //NSMakeRange表示所要的范围,从0到整个文本的长度
    [str addAttribute:NSParagraphStyleAttributeName value:par range:NSMakeRange(0, lable.text.length)];

    [lable setAttributedText:str];

效果图:

• 11.点击button倒计时

//第一种方法
//点击button倒计时
#import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong) UIButton * timeButton;
@property (nonatomic, strong) NSTimer * timer;
@property (nonatomic, strong)UIButton * btn;

@end

@implementation ViewController
{
    NSInteger _time;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    _time = 5;

    self.btn = [UIButton buttonWithType:UIButtonTypeCustom];
    _btn.backgroundColor = [UIColor orangeColor];
    [_btn setTitle:@"获取验证码" forState:UIControlStateNormal];
    _btn.titleLabel.font = [UIFont systemFontOfSize:15];
    [_timeButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    [_btn addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
    [self refreshButtonWidth];
    [self.view addSubview:self.btn];
}
- (void)refreshButtonWidth
{
    CGFloat width = 0;
    if (_btn.enabled) {
        width = 100;
    }
    else {
        width = 200;
    }
    _btn.center = CGPointMake(self.view.frame.size.width/2, 200);
    _btn.bounds = CGRectMake(0, 0, width, 40);
    //每次刷新，保证区域正确
    [_btn setBackgroundImage:[self imageWithColor:[UIColor orangeColor] andSize:_btn.frame.size] forState:UIControlStateNormal];
    [_btn setBackgroundImage:[self imageWithColor:[UIColor lightGrayColor] andSize:_btn.frame.size] forState:UIControlStateDisabled];
}
- (UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)aSize
{
    CGRect rect = CGRectMake(0.0f, 0.0f, aSize.width, aSize.height);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

- (void)btnAction:(UIButton *)sender
{
    sender.enabled = NO;
    [self refreshButtonWidth];
    [sender setTitle:[NSString stringWithFormat:@"获取验证码(%zi)", _time] forState:UIControlStateNormal];

    _timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(timeDown) userInfo:nil repeats:YES];
}

- (void)timeDown
{
    _time --;
    if (_time == 0) {
        [_btn setTitle:@"重新获取" forState:UIControlStateNormal];
        _btn.enabled = YES;
        [self refreshButtonWidth];

        [_timer invalidate];
        _timer = nil;
        _time = 5 ;
        return;
    }
    [_btn setTitle:[NSString stringWithFormat:@"获取验证码(%zi)", _time] forState:UIControlStateNormal];
}

//第二种方法
#pragma mark -点击发送验证码
- (void)sendMessage:(UIButton *)btn
{

    if (self.phoneField.text.length == 0) {
        [self remindMessage:@"请输入正确的手机号"];

    }else{
        __block int timeout=60; //倒计时时间
        dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
        dispatch_source_t _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue);
        dispatch_source_set_timer(_timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒执行
        dispatch_source_set_event_handler(_timer, ^{
            if(timeout<=0){ //倒计时结束，关闭
                dispatch_source_cancel(_timer);
                dispatch_async(dispatch_get_main_queue(), ^{
                    //                设置界面的按钮显示 根据自己需求设置
                    [btn setTitle:@"发送验证码" forState:UIControlStateNormal];
                    btn.userInteractionEnabled = YES;
                });
            }else{
                int seconds = timeout % 60;
                NSString *strTime = [NSString stringWithFormat:@"%d", seconds];
                if ([strTime isEqualToString:@"0"]) {
                    strTime = [NSString stringWithFormat:@"%d",60];
                }
                dispatch_async(dispatch_get_main_queue(), ^{
                    //设置界面的按钮显示 根据自己需求设置
                    //NSLog(@"____%@",strTime);
                    [UIView beginAnimations:nil context:nil];
                    [UIView setAnimationDuration:1];
                    [btn setTitle:[NSString stringWithFormat:@"%@秒后重新发送",strTime] forState:UIControlStateNormal];
                    [UIView commitAnimations];
                    btn.userInteractionEnabled = NO;
                });
                timeout--;
            }
        });
        dispatch_resume(_timer);
}

效果图:

• 1. UITextField默认占位符是居中显示,让其居上显示

 textField.contentVerticalAlignment = UIControlContentVerticalAlignmentTop;

• 13.拍照,获取相机的相册,并自定义相机界面

#import "ViewController.h"

@interface ViewController ()<UIImagePickerControllerDelegate,UINavigationControllerDelegate>
@property (nonatomic, strong)UIImagePickerController * picker;
@property (nonatomic, strong)UIImageView * imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    self.imageView = [[UIImageView alloc]initWithFrame:CGRectMake(50, 50, 250, 250)];
    _imageView.backgroundColor = [UIColor grayColor];
    [self.view addSubview:self.imageView];

    UIButton * btn = [UIButton buttonWithType:UIButtonTypeCustom];
    btn.frame = CGRectMake(100, 350, 100, 50);
    btn.backgroundColor = [UIColor greenColor];
    [btn setTitle:@"保存图片" forState:UIControlStateNormal];
    [btn addTarget:self action:@selector(doClick:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
}
- (void)doClick:(UIButton *)sender
{
    //创建图片选择控制器对象
    self.picker = [[UIImagePickerController alloc]init];
    //设置代理
    _picker.delegate = self;
    //设置样式
    /**
     *   UIImagePickerControllerSourceTypePhotoLibrary,//从相册打开照片
     UIImagePickerControllerSourceTypeCamera,//启动摄像头拍照
     UIImagePickerControllerSourceTypeSavedPhotosAlbum//直接打开保存的照片列表,如果有摄像头,则打开相册
     */
    UIImagePickerControllerSourceType type = UIImagePickerControllerSourceTypeCamera;
    _picker.sourceType = type;
    //允许编辑(选择好图片或者拍摄好之后允许用户拖动缩放等操作)
    _picker.allowsEditing = YES;
    //弹出相机
    [self presentViewController:self.picker animated:YES completion:^{

    }];

    //自定义相机界面
    _picker.showsCameraControls = NO;

    UIToolbar * tool = [[UIToolbar  alloc]initWithFrame:CGRectMake(0, self.view.frame.size.height - 40, self.view.frame.size.width, 40)];
    tool.barStyle = UIBarStyleBlackTranslucent;
    tool.barTintColor = [UIColor greenColor];

    UIBarButtonItem * cancel = [[UIBarButtonItem alloc]initWithTitle:@"取消" style:UIBarButtonItemStylePlain target:self action:@selector(touchCancel)];
    cancel.width = self.view.frame.size.width/2;

    UIBarButtonItem * ok = [[UIBarButtonItem alloc]initWithTitle:@"确定" style:UIBarButtonItemStylePlain target:self action:@selector(touchOk)];
    ok.width = self.view.frame.size.width/2;

    [tool setItems:@[cancel,ok]];
    //把自定义的view添加到UIImagePickerController的layView上
    _picker.cameraOverlayView = tool;


}
#pragma mark - UIImagePickerControllerDelegate
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
{
    //从字典中取出照片
    /*
     UIImagePickerControllerEditedImage 编辑之后的图片
     UIImagePickerControllerOriginalImage 原来的图片
    */
    UIImage * image = [info objectForKey:UIImagePickerControllerOriginalImage];
    self.imageView.image = image;
    //相机消失
    [self dismissViewControllerAnimated:YES completion:^{

    }];


}
#pragma mark - 取消按钮和确定按钮
- (void)touchCancel
{
    [self.picker dismissViewControllerAnimated:YES completion:^{

    }];
}
- (void)touchOk
{
    [self.picker takePicture];
}