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[英]iOS App UILabel crashed when I change text size from iOS Settings Screen
[英]Screen doesn't update when I change a UILabel's text
我的環境是Xcode 6.3,目標是iPad的iOS8.3。 我正在使用Xcode的模板學習“主從視圖”。 當我嘗試在詳細信息視圖中設置標簽的文本時,出現一些奇怪的問題:
如果我將更改標簽文本的語句放在P1位置,則它可以工作。
但是,如果我將該聲明置於P2位置,則它不起作用。
在這兩種情況下,detailDescriptionLabel.text均已更改,但只有P1語句實際更新了屏幕。(我檢查過兩次都調用了configureView()函數)
有人可以幫我嗎? 非常感謝。
以下是我的代碼段:
MasterController.m:
#import "MasterViewController.h"
#import "DetailViewController.h"
@interface MasterViewController ()
@property (copy, nonatomic) NSMutableArray *objects;
@end
@implementation MasterViewController
- (void)awakeFromNib {
[super awakeFromNib];
self.clearsSelectionOnViewWillAppear = NO;
self.preferredContentSize = CGSizeMake(320.0, 600.0);
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSString *path = [[NSBundle mainBundle] pathForResource:@"PresidentList" ofType:@"plist"];
NSDictionary *presidentInfo = [NSDictionary dictionaryWithContentsOfFile:path];
self.objects = [NSMutableArray arrayWithArray:[presidentInfo objectForKey:@"presidents"]];
self.detailViewController = (DetailViewController *)[[self.splitViewController.viewControllers lastObject] topViewController];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Segues
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([[segue identifier] isEqualToString:@"showDetail"]) {
DetailViewController *controller = (DetailViewController *)[[segue destinationViewController] topViewController];
controller.navigationItem.leftBarButtonItem = self.splitViewController.displayModeButtonItem;
controller.navigationItem.leftItemsSupplementBackButton = YES;
//P1
//controller.detailItem = (self.objects[indexPath.row])[@"url"];
}
}
#pragma mark - Table View
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return self.objects.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
cell.textLabel.text = (self.objects[indexPath.row])[@"name"];
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
//P2
//self.detailViewController.detailItem = (self.objects[indexPath.row])[@"url"];
}
@end
DetailController.m:
#import "DetailViewController.h"
@interface DetailViewController ()
@property (strong, nonatomic) UIPopoverController *masterPopoverController;
@end
@implementation DetailViewController
#pragma mark - Managing the detail item
- (void)setDetailItem:(id)newDetailItem {
if (_detailItem != newDetailItem) {
_detailItem = newDetailItem;
// Update the view.
[self configureView];
}
if (self.masterPopoverController != nil) {
[self.masterPopoverController dismissPopoverAnimated:YES];
}
}
- (void)configureView {
// Update the user interface for the detail item.
if (self.detailItem) {
self.detailDescriptionLabel.text = self.detailItem;
}
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self configureView];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Split view
- (void)splitViewController:(UISplitViewController *)svc willHideViewController:(UIViewController *)aViewController withBarButtonItem:(UIBarButtonItem *)barButtonItem forPopoverController:(UIPopoverController *)pc {
barButtonItem.title = NSLocalizedString(@"Master", @"Master");
[self.navigationItem setLeftBarButtonItem:barButtonItem animated:YES];
self.masterPopoverController = pc;
}
- (void)splitViewController:(UISplitViewController *)svc willShowViewController:(UIViewController *)aViewController invalidatingBarButtonItem:(UIBarButtonItem *)barButtonItem {
[self.navigationItem setLeftBarButtonItem:nil animated:YES];
self.masterPopoverController = nil;
}
@end
我猜您正在使用segues,這就是使用適當指定的專用函數( prepareForSegue
)來創建視圖目標視圖之后初始化值的意義。
除非您實例化並在didSelectRowAtIndexPath
顯示視圖,否則沒有必要為此類viewcontroller設置內容。
我會猜測self.detailViewController為零。 因此,P2將不起作用。
在看不到所有代碼的情況下很難說,但是在prepareForSegue中,您可能想要在此處分配它。
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