更新UIAlertView消息動態和換行符問題

Question

我需要在我的UIAlertView的消息中顯示多行文本。我曾嘗試添加'\ n'，但它沒有效果。它仍然顯示：「這是一個例子....」。然而，如果我將我的iPhone變成橫向模式，它會按照我的意圖顯示消息。然後如果我切換回肖像模式，它也會正確顯示。

更新：經過進一步的考慮，我懷疑它與我正在用新（更長的）字符串更新當前消息的事實有關。我已經在alert視圖上調用了「show」，並試圖更新消息。也許有些東西需要重新繪製？就像我以前說過的那樣，如果我改變方向，它會正確顯示（不管我從哪個方向開始，我仍然有同樣的問題）。我已經嘗試過「setNeedsDisplay」和「setNeedsLayout」。

Answer 1

雖然我相信更新警報視圖中的文本，而真實顯示這是錯誤的，我看到改變的唯一方式就是這樣

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"test" message:@"this is a message\nthis is a new line text" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:@"test button",nil]; 
[alert show]; 

//set the new message 
NSString *newMessage = [NSString stringWithString:@"Test\nWith a new message with\ncustom new line string\n and a lot\n of new lines\n Yep"]; 
[alert setMessage:newMessage]; 

//get the original alert Frame 
CGRect alertFrame = alert.frame; 
//get the alert view Label 
UILabel *alertLabel = [alert.subviews objectAtIndex:2]; 
//and get the original frame position 
CGRect alertLabelFrame = alertLabel.frame; 

//see how much space we are needing for the new message and adjust 
int heightChange = [newMessage sizeWithFont:[UIFont systemFontOfSize:16] constrainedToSize:CGSizeMake(alertLabelFrame.size.width, MAXFLOAT) lineBreakMode:UILineBreakModeWordWrap].height - alertLabelFrame.size.height; 

alertFrame.size.height += heightChange; 
//adjust the Label height to the new height 
alertLabelFrame.size.height += heightChange; 

//adjust the frame and elements with an animation for smoothness 
[UIView animateWithDuration:0.15 delay:0.4 options:(UIViewAnimationCurveEaseIn) animations:^{ 
    [alert setFrame:alertFrame];   
    alertLabel.frame = alertLabelFrame; 
    //move any buttons 
    for (UIView *subView in alert.subviews) { 
     if ([subView isKindOfClass:[UIButton class]]) { 
      //this is a button move it 
      UIButton *button = (UIButton*)subView; 
      CGRect alertButtonFrame = button.frame; 
      //adjust button Y position to the new height 
      alertButtonFrame.origin.y += heightChange-5; 
      button.frame = alertButtonFrame; 
     } 
    } 
} completion:nil]; 

Answer 2

對於換行符使用\ n換行字符在文本中是這樣的：

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"test" message:@"this is a message\nthis is a new line text" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil]; 
[alert show]; 
[alert release]; 

即使setMessage這個工程：

UIAlertView *alert = [[UIAlertView alloc] init]; 
[alert setMessage:@"this is\na test"]; 
[alert show]; 
[alert release]; 

Answer 3

使用 '\ r' 符號。它應該正確斷線。

Answer 4

下面是一些簡單的代碼來調整在警報的消息。請注意，警報的框架需要足夠大。您可以使用幾條換行符填充初始警報。

for (UILabel *l in alertView.subviews){ 
    if ([l isKindOfClass:[UILabel class]]){ 
     float w = l.frame.size.width; 
     [l setNumberOfLines:0]; 
     [l sizeToFit]; 
     CGRect r = l.frame; 
     r.size.width = w; 
     l.frame = r; 
    } 
} 

Answer 5

1. 創建自己的AlertView類別。

AlertWithBlock.h文件

#import <UIKit/UIKit.h> 

@interface UIAlertView (AlertWithBlock) 

- (void (^)(UIAlertView *alertView, NSInteger buttonIndex))delegateBlock; 

- (void)setDelegateBlock:(void (^)(UIAlertView *alertView, NSInteger buttonIndex))delegateBlock; 


+ (void)alertViewWithTitle:(NSString *)title buttonTitle:(NSString *)buttonTitle message:(NSString *)message; 

+ (UIAlertView *)alertWithTitle:(NSString *)title message:(NSString *)message cancelButtonTitle:(NSString *)cancelButtonTitle otherButtonTitles:(NSArray *)otherButtonTitles delegate:(void (^)(UIAlertView *alertView, NSInteger buttonIndex))delegate; 

@end