iOS8开发之iOS8的UIAlertController
在iOS8之前用UIActionSheet和UIAlertView来提供按钮选择和提示性信息，比如UIActionSheet可以这样写：
UIActionSheet *actionSheet = [[UIActionSheet alloc]
initWithTitle:@"title,nil时不显示"
delegate:self
cancelButtonTitle:@"取消"
destructiveButtonTitle:@"确定"
otherButtonTitles:@"第一项", @"第二项",nil];
actionSheet.actionSheetStyle = UIActionSheetStyleBlackOpaque;
[actionSheet showInView:self.view];
然后在协议中实现代理:
(void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
if (buttonIndex == 0) {
NSLog(@"确定");
}else if (buttonIndex == 1) {
NSLog(@"第一项");
}else if(buttonIndex == 2) {
NSLog(@"第二项");
}else if(buttonIndex == actionSheet.cancleButtonIndex) {
NSLog(@"取消");
}
}
- (void)actionSheetCancel:(UIActionSheet *)actionSheet{
}
-(void)actionSheet:(UIActionSheet *)actionSheet didDismissWithButtonIndex:(NSInteger)buttonIndex{
}
-(void)actionSheet:(UIActionSheet *)actionSheet willDismissWithButtonIndex:(NSInteger)buttonIndex{
}
如果需要修改按钮字体、颜色等可以实现以下代理：
- (void)willPresentActionSheet:(UIActionSheet *)actionSheet {
for (UIView *subViwe in actionSheet.subviews) {
if ([subViwe isKindOfClass:[UILabel class]]) {
UILabel *label = (UILabel *)subViwe;
label.font = [UIFont systemFontOfSize:16];
label.frame = CGRectMake(CGRectGetMinX(label.frame), CGRectGetMinY(label.frame), CGRectGetWidth(label.frame), CGRectGetHeight(label.frame)+20);
}
if ([subViwe isKindOfClass:[UIButton class]]) {
UIButton *button = (UIButton*)subViwe;
if ([button.titleLabel.text isEqualToString:@"确定"]) {
[button setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
} else {
[button setTitleColor:[WTDevice getGreenColor] forState:UIControlStateNormal];
}
button.titleLabel.font = [UIFont systemFontOfSize:18];
}
}
}
以上代码（代理部分），在ios7及以下版本中是有效的，但是在iOS8中却不起作用，因为iOS8抛弃了UIActionSheet和UIAlertView，取而代之的是UIAlertController，其使用方法如下(代替UIAlertView)：
#ifdef __IPHONE_8_0
if (TARGET_IS_IOS8) {
UIAlertController *actionSheetController = [UIAlertController alertControllerWithTitle:@"提示"
message:@"需要设置允许访问相机，操作方法见“设置”->“帮助中心”"
preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *actionCancel = [UIAlertAction actionWithTitle:@"确定"
style:UIAlertActionStyleDestructive
handler:^(UIAlertAction * action) {}];
[actionSheetController addAction:actionCancel];
[actionSheetController.view setTintColor:[WTDevice getGreenColor]];
[self presentViewController:actionSheetController animated:YES completion:nil];
}
#endif
if (TARGET_NOT_IOS8) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示" message:@"需要设置允许访问相机，操作方法见“设置”->“帮助中心”" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:nil];
[alert show];
}
代替UIActionSheet：
#ifdef __IPHONE_8_0
if (TARGET_IS_IOS8) {
UIAlertController *actionSheetController = [UIAlertController alertControllerWithTitle:@"action选项"
message:nil
preferredStyle:UIAlertControllerStyleActionSheet];
UIAlertAction *action0 = [UIAlertAction actionWithTitle:@"选项一"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
[self customMethod1];
}];
[actionSheetController addAction:action0];
UIAlertAction *action = [UIAlertAction actionWithTitle:@"选项二"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
[self <span style="font-family: Arial, Helvetica, sans-serif;">customMethod2</span>];
}];
UIAlertAction *action1 = [UIAlertAction actionWithTitle:@"选项三"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
[self customMethod3];
}];
UIAlertAction *actionCancel = [UIAlertAction actionWithTitle:@"取消"
style:UIAlertActionStyleCancel
handler:^(UIAlertAction * action) {}];
[actionSheetController addAction:action];
[actionSheetController addAction:action1];
[actionSheetController addAction:actionCancel];
[actionSheetController.view setTintColor:[UIColor greenColor]];
[self presentViewController:actionSheetController animated:YES completion:nil];
}
#endif
if (TARGET_NOT_IOS8) {
UIActionSheet *as = [[UIActionSheet alloc] initWithTitle:@"action选项" delegate:self cancelButtonTitle:@"取消" destructiveButtonTitle:nil otherButtonTitles:@"选项一",@"选项二",@"选项三", nil];
[as showInView:self.view];
}
至于两者的区别，可以看到，iOS8之前是在controller的view上边又覆盖了一层view，iOS8之后则是present了一个controller并且将代理换成了block，代码显得更加紧凑。
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