当我们在一个控制视图上，在UITextField输入文字信息之后，希望可以使用键盘的Done触发一个 Done的UIButton，但是刚开始我直接在
-(BOOL)textFieldShouldReturn:(UITextField *)textField 内调用按键的行为： - (IBAction)DonePhotoButton:(UIButton *)sender {
//代码 } 虽然可以执行到{}内的代码，但是不会触发按键按下之后一个Unwind Segue(解散当前视图，退回上一个视图，并完全一个方法)，也就是说没有触发退回上一个视图然后再执行一个AddPhoto：方法，寻思着，为什么没有触发Unwind Segue，于是仔细查看最终找到了解决办法。
IPhone 上的视图：
在Storyboard里的unwind Segue:
我这里的代码是使用
[self performSegueWithIdentifier:kUNWIND_ID sender:nil];
强制执行一个带Identifier的Segue，并且判断是否符合要求，实验证明这是可行的
执行的代码：
- (IBAction)DonePhotoButton:(UIButton *)sender {
}//按键事件
#pragma mark - prepareForSegue
//prepare
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if ([segue.identifier isEqualToString:kUNWIND_ID]) {
NSManagedObjectContext * context = self.photographyerTakingPhoto.managedObjectContext;
if (context) {
Photo * photo = [NSEntityDescription insertNewObjectForEntityForName:@"Photo" inManagedObjectContext:context];
photo.title = self.TextFieldTitle.text;
photo.subtitle = self.TextFieldSubTitle.text;
photo.whoTook = self.photographyerTakingPhoto;
photo.latitude = [NSNumber numberWithDouble:self.location.coordinate.latitude];
photo.longitude = [NSNumber numberWithDouble:self.location.coordinate.longitude];
photo.imageURL = [self.imageURL absoluteString];
photo.thumbnailURL = [self.thumnailURL absoluteString];
self.photo = photo;
}
}
}
//判断identifer 决定是否执行prepareForSegue 同时给出警告
-(BOOL) shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender{
if ([identifier isEqualToString:kUNWIND_ID]) {
if (!self.image) {
[self alert:@"No Photo taken!"];
return NO;
}else if(![self.TextFieldTitle.text length] || ![self.TextFieldSubTitle.text length]){
[self.TextFieldTitle.text length] ? [self alert:@"SubTitle required!"] :
[self.TextFieldSubTitle.text length] ? [self alert:@"Title required!"] : [self alert:@"Title and SubTitle required"] ;
return NO;
}else{
return YES;
}
}else{
return [super shouldPerformSegueWithIdentifier:identifier sender:sender];
}
}
//----------------------------------------------------------------//
//点击键盘的return取消键盘
-(BOOL)textFieldShouldReturn:(UITextField *)textField{
[textField resignFirstResponder];
BOOL CanSegue = [self shouldPerform:kUNWIND_ID];
if (CanSegue)
[self performSegueWithIdentifier:kUNWIND_ID sender:nil];
return YES;
}
-(BOOL) shouldPerform:(NSString *)identifier {
if ([identifier isEqualToString:kUNWIND_ID]) {
if (!self.image) {
[self alert:@"No Photo taken!"];
return NO;
}else if(![self.TextFieldTitle.text length] || ![self.TextFieldSubTitle.text length]){
[self.TextFieldTitle.text length] ? [self alert:@"SubTitle required!"] :
[self.TextFieldSubTitle.text length] ? [self alert:@"Title required!"] : [self alert:@"Title and SubTitle required"] ;
return NO;
}else{
return YES;
}
}else{
return NO;
}
}