iOS开发从入门到精通-- 警告对话框UIAlertView和等待提示器UIActivityIndicatorView

警告对话框UIAlertView和等待提示器UIActivityIndicatorView:
1.UIAlertView简单一点就是弹框
2.就是所谓的菊花转圈圈

声明：注意@interface ViewController : UIViewController<UIAlertViewDelegate>这个里面多了一个UIAlertViewDelegate代理

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UIAlertViewDelegate>{

    //定义一个警告对话框视图对象
    UIAlertView * _alertView;

    //等待提示对象
    //当下载，或者加载比较大的文件时，可以显示此控件，处于提示等待状态
    UIActivityIndicatorView * _activityIndicator;
}

@property(retain,nonatomic) UIAlertView * alertView;
@property(retain,nonatomic) UIActivityIndicatorView * activityIndicator;


@end

实现：

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

//实现属性和成员变量的同步
@synthesize alertView =_alertView;
@synthesize activityIndicator=_activityIndicator;

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    for(int i=0;i<2;i++){
        UIButton * btn =[UIButton buttonWithType:UIButtonTypeRoundedRect];
        btn.frame = CGRectMake(100, 100+100*i, 100, 40);
        if(i==0){
            [btn setTitle:@"警告对话框" forState:UIControlStateNormal];
        }
        else if(i==1){
            [btn setTitle:@"等待指示器" forState:UIControlStateNormal];
        }

        btn.tag = 101+i;

        [btn addTarget:self action:@selector(pressBtn:) forControlEvents:UIControlEventTouchUpInside];

        [self.view addSubview:btn];
    }
}

-(void) pressBtn:(UIButton*) btn{
    //警告对话框创建
    //p1:对话框标题
    //p2:提示信息
    //p3:处理按钮事件的代理对象
    //p4:取消按钮的文字,默认的索引为0；
    //p5:其他按钮文字 ** otherButtonTitles:@"确定", nil]; 只有取消和确定按钮是横向排开
    // otherButtonTitles:@"确定",@"确定1",@"确定2", nil];这样子就会全部纵向排开，索引依次是1，2，3.
    //p6:...:添加其他按钮
    //nil:表示按钮添加结束
    if(btn.tag==101){
        _alertView = [[UIAlertView alloc]initWithTitle:@"警告"
                                               message:@"你的手机电量过低，请保存数据"
                                              delegate:self
                                     cancelButtonTitle:@"取消"
                                     otherButtonTitles:@"确定", nil];

        //显示对话框
        [_alertView show];
    }
    //创建等待提示器，大伙都叫他菊花
    else if(btn.tag==102){
        //创建等待提示器，宽高不可变更
        _activityIndicator =[[UIActivityIndicatorView alloc]initWithFrame:CGRectMake(100, 300, 80, 80)];

        //设定提示的风格:小灰，小白，大白
        _activityIndicator.activityIndicatorViewStyle =UIActivityIndicatorViewStyleGray;//小灰

//        _activityIndicator.activityIndicatorViewStyle=UIActivityIndicatorViewStyleWhite;//小白
//        
//        _activityIndicator.activityIndicatorViewStyle=UIActivityIndicatorViewStyleWhiteLarge;//大白

//        self.view.backgroundColor=[UIColor blueColor];

        [self.view addSubview:_activityIndicator];

        //启动动画并显示
        [_activityIndicator startAnimating];

        //停止等待动画并隐藏
//        [_activityIndicator stopAnimating];

    }
}

//当点击对话框的按钮时，调用此函数
//p1:对话框对象本身
//p2:按钮的索引
-(void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
    NSLog(@"index=%ld\n",buttonIndex);
}

//对话框即将消失，此函数被调用
-(void) alertView:(UIAlertView *)alertView willDismissWithButtonIndex:(NSInteger)buttonIndex{
    NSLog(@"即将消失！");
}

//对话框已经消失时，调用此函数
-(void) alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex{
    NSLog(@"已经消失");
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end