• UIPickerView简单应用


    下面是一些效果图

    下面是代码。有些枯燥 , 其实并不难 。

    #import <UIKit/UIKit.h>
    
    @interface ViewController : UIViewController<UIPickerViewDelegate,UIPickerViewDataSource>
    
    @property(strong,nonatomic) UIPickerView *picker;
    @property(strong,nonatomic) NSMutableArray *sheng;
    @property(strong,nonatomic) NSMutableArray *shi;
    @property(strong,nonatomic) NSArray *array;
    
    @end
    
    #import "ViewController.h"
    
    @interface ViewController ()
    
    @end
    
    @implementation ViewController
    
    - (void)viewDidLoad {
        [super viewDidLoad];
        self.sheng=[NSMutableArray array];
        self.shi=[NSMutableArray array];
        NSBundle *bundle=[NSBundle mainBundle];
        NSString *path=[bundle pathForResource:@"city.plist" ofType:nil];
        self.array=[NSArray arrayWithContentsOfFile:path];
        for (NSDictionary *ar1 in self.array) {
            NSArray *ar2=[ar1 objectForKey:@"Cities"];
            [self.sheng addObject:[ar1 objectForKey:@"State"]];
            for (NSDictionary *ar3 in ar2) {
    //            NSLog(@"%@",[ar3 objectForKey:@"city"]);
            [self.shi addObject:[ar3 objectForKey:@"city"]];
                
            }
            
            
        }
    
        self.picker=[[UIPickerView alloc]initWithFrame:CGRectMake(0, 200, 414, 300)];
        self.picker.backgroundColor=[UIColor greenColor];
        
        [self.view addSubview: self.picker];
        self.picker.delegate=self;
        self.picker.dataSource=self;
        
    }
    
    #pragma mark -数据源  nubertOfComponentsInPickerView:
    -(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
    {
        return 2;
    }
    
    #pragma mark - 数据源 pickerView: attributedTitleForRow: forComponent:
    -(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
        
     
        
        if (component==0) {
            return self.sheng.count;
        }
             return self.shi.count;
    }
    
    
    #pragma mark - 显示信息方法  delegate
    -(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
    {
        if (component==0) {
            return self.sheng[row];
            
        }
        
       
             return self.shi[row];
    }
    #pragma mark -选中行的信息
    -(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
    {
        if (component==0) {
            //清除上次选择地城市
            [self.shi removeAllObjects];
            NSDictionary *dic=[self.array objectAtIndex:row];
    //          NSLog(@"%@",dic);
            NSArray *arr1=dic[@"Cities"];
          
    
            NSMutableArray * arr2 =[NSMutableArray array];
            for (NSDictionary * dic in arr1) {
                [arr2 addObject:dic[@"city"]];
                
               
            }
            self.shi=arr2;
            [self.picker selectRow:row inComponent:0 animated:YES];
            
            [self.picker reloadComponent:1];
            
            }
        else {
            NSInteger firstRow=[self.picker selectedRowInComponent: 0];
            NSInteger secondRow=[self.picker selectedRowInComponent:1];
            
            NSString *firstString=[self.sheng objectAtIndex:firstRow];
            NSString *secondString=[self.shi objectAtIndex:secondRow];
            
            
            NSString *message=[NSString stringWithFormat:@"您确定要选择%@%@吗?",firstString,secondString];
            UIAlertController *alertMessage=[UIAlertController alertControllerWithTitle:@"提示" message:message preferredStyle:UIAlertControllerStyleAlert];
            
            UIAlertAction *cancle=[UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];
            
            UIAlertAction *ok=[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:nil];
            
            [alertMessage addAction:cancle];
            [alertMessage addAction:ok];
            [self presentViewController:alertMessage animated:YES completion:nil];
            NSLog(@"%@%@",firstString,secondString);
    
        }
        
            
        }
    
        
    
    #pragma mark - 行高
    -(CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component
    {
        if (component==0) {
             return  80;
        }
        return 50;
    }
    
    - (void)didReceiveMemoryWarning {
        [super didReceiveMemoryWarning];
        // Dispose of any resources that can be recreated.
    }
    
    @end
    
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    第四十二个知识点:看看你的C代码为蒙哥马利乘法,你能确定它可能在哪里泄漏侧信道路吗?
  • 原文地址:https://www.cnblogs.com/fume/p/5267291.html
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