[一句秒懂] iOS8.0-UIAlertController介绍

一 概述

在IOS8之后，UIAlertController替代了UIActionSheet和UIAlertView。把两种类型的提示信息放到这一个类里来实现。
注意， 这个class不能通过继承的方式来自定义。
二 类介绍

先举两个使用的例子
例子一
IOS SDK详解之UIAlertController(IOS8之后替代AlertView和ActionSheet)0

UIAlertController * alertController = [UIAlertController alertControllerWithTitle: nil                                                                             message: nil                                                                       preferredStyle:UIAlertControllerStyleActionSheet];
//添加Button
[alertController addAction: [UIAlertAction actionWithTitle: @"拍照" style: UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
//处理点击拍照
}]];
[alertController addAction: [UIAlertAction actionWithTitle: @"从相册选取" style: UIAlertActionStyleDefault handler:^(UIAlertAction *action){
//处理点击从相册选取
}]];
[alertController addAction: [UIAlertAction actionWithTitle: @"取消" style: UIAlertActionStyleCancel handler:nil]];

[self presentViewController: alertController animated: YES completion: nil];

例子二
IOS SDK详解之UIAlertController(IOS8之后替代AlertView和ActionSheet)1
实现代码

UIAlertController * alertController = [UIAlertController alertControllerWithTitle: @"登陆"
message: @"输入用户名密码"
preferredStyle:UIAlertControllerStyleAlert];
[alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
textField.placeholder = @"name";
textField.textColor = [UIColor blueColor];
textField.clearButtonMode = UITextFieldViewModeWhileEditing;
textField.borderStyle = UITextBorderStyleRoundedRect;
}];
[alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
textField.placeholder = @"password";
textField.textColor = [UIColor blueColor];
textField.clearButtonMode = UITextFieldViewModeWhileEditing;
textField.borderStyle = UITextBorderStyleRoundedRect;
textField.secureTextEntry = YES;
}];
[alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
NSArray * textfields = alertController.textFields;
UITextField * namefield = textfields[0];
UITextField * passwordfiled = textfields[1];
NSLog(@"%@:%@",namefield.text,passwordfiled.text);

}]];
[self presentViewController:alertController animated:YES completion:nil];

三 使用的步骤

第一步 初始化

+ (instancetype)alertControllerWithTitle:(NSString *)title
message:(NSString *)message
preferredStyle:(UIAlertControllerStyle)preferredStyle

这里的preferredStyle有两种，sheet和alert

typedef enum UIAlertControllerStyle: NSInteger {
UIAlertControllerStyleActionSheet = 0,
UIAlertControllerStyleAlert
} UIAlertControllerStyle;

第二步，添加Action（button或者textfield）
添加Button
- (void)addAction:(UIAlertAction *)action
这里的UIAlertAction是一个比较简单的类

+ (instancetype)actionWithTitle:(NSString *)title
style:(UIAlertActionStyle)style
handler:(void (^)(UIAlertAction *action))handler

style有三种

typedef enum UIAlertActionStyle: NSInteger {
UIAlertActionStyleDefault = 0,//默认
UIAlertActionStyleCancel,//取消
UIAlertActionStyleDestructive //有可能改变或者数据
} UIAlertActionStyle;

添加TextField
注意，只能是 UIAlertControllerStyleAlert才能添加Textfield

- (void)addTextFieldWithConfigurationHandler:(void (^)(UITextField *textField))configurationHandler

在block里配置textfield的信息，例如placeholder，backgroundcolor等。
Textfield的保存信息可由UIAlertController的属性Textfields获得。如同上述的例子二一样。

第三步，显示
例如

[self presentViewController:alert animated:YES completion:nil];

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:nil message:@"选择照片来源" preferredStyle:UIAlertControllerStyleActionSheet];

UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
imagePickerController.delegate = self;
imagePickerController.allowsEditing = YES;

UIAlertAction *albumAction = [UIAlertAction actionWithTitle:@"从相册选取" style:(UIAlertActionStyleDefault) handler:^(UIAlertAction *action) {
imagePickerController.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
[self presentViewController:imagePickerController animated:YES completion:^{}];
}];

UIAlertAction *photoAction = [UIAlertAction actionWithTitle:@"拍照" style:(UIAlertActionStyleDefault) handler:^(UIAlertAction *action) {
imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
[self presentViewController:imagePickerController animated:YES completion:^{
}];
}];

UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"取消" style:(UIAlertActionStyleCancel) handler:^(UIAlertAction *action){
// 可以不用书写代码
}];
[self presentViewController:alertController animated:YES completion:nil];

//用来判断来源 Xcode中的模拟器是没有拍摄功能的,当用模拟器的时候我们不需要把拍照功能加速
if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

[alertController addAction:albumAction];
[alertController addAction:photoAction];
[alertController addAction:cancelAction];
}else {

[alertController addAction:albumAction];
[alertController addAction:cancelAction];
}