如何在objective c中检查UIView是否为零 [英] How to check UIView is nil or not in objective c
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问题描述
我是 iOS 新手,我在验证视图方面遇到了问题.我创建了像视图一样的签名
我想做验证.
如果我没有签名,它会显示消息.
请给我建议.
提前致谢!
我保存图像和使用条件
UIGraphicsBeginImageContext(self.drawSignView.bounds.size);[[self.drawSignView.layerpresentationLayer] renderInContext:UIGraphicsGetCurrentContext()];UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();//NSData *postData = UIImageJPEGRepresentation(viewImage, 1.0);//存储数据NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];NSData *imageData = UIImageJPEGRepresentation(viewImage, 100);[默认 setObject:imageData forKey:@"image"];[默认同步];如果(视图图像==零){UIAlertView *alertviewshow =[[UIAlertView alloc] initWithTitle:@"警告!"message:@"Pease Sign" delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK", nil];[alertviewshow setTag:1];[alertviewshow 显示];}
但它不起作用,因为它包含空白图像.
解决方案
请检查这个答案
UIGraphicsBeginImageContext(self.drawSignView.bounds.size);[[self.drawSignView.layerpresentationLayer] renderInContext:UIGraphicsGetCurrentContext()];UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();//NSData *postData = UIImageJPEGRepresentation(viewImage, 1.0);NSData *imgData = [[NSData alloc] initWithData:UIImageJPEGRepresentation((viewImage), 0.5)];int imageSize = imgData.length;NSLog(@"图片大小KB: %d ", imageSize/1024);UIGraphicsBeginImageContext(self.drawSignViewClient.bounds.size);[[self.drawSignViewClient.layerpresentationLayer] renderInContext:UIGraphicsGetCurrentContext()];UIImage *viewImageClient = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();//NSData *postData = UIImageJPEGRepresentation(viewImage, 1.0);NSData *imgDataClient = [[NSData alloc] initWithData:UIImageJPEGRepresentation((viewImageClient), 0.5)];int imageSizeClient = imgDataClient.length;NSLog(@"图片大小KB: %d ", imageSizeClient/1024);int OCS=imageSize/1024;int Client=imageSizeClient/1024;如果(OCS<3){alertviewshow=[[UIAlertView alloc] initWithTitle:@"警告!"message:@"请签名" delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK", nil];[alertviewshow setTag:1];[alertviewshow 显示];}否则如果(客户端<3){alertviewshow=[[UIAlertView alloc] initWithTitle:@"警告!"message:@"请签名" delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK", nil];[alertviewshow setTag:1];[alertviewshow 显示];}别的{//写你的代码....}
I am new in iOS and I am facing problem regarding to do validation of view. I have created Signature like view How to draw Signature on UIView, and now I want to do validation by using this code
-(IBAction)SavebtnClick:(id)sender
{
if(drawSignView==nil)
{
UIAlertView *alertviewshow =[[UIAlertView alloc] initWithTitle:@"Warning!" message:@"Pease Sign" delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK", nil];
[alertviewshow show];
}
else if (drawSignViewClient==nil)
{
UIAlertView *alertviewshow =[[UIAlertView alloc] initWithTitle:@"Warning!" message:@"Please Sign" delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK", nil];
[alertviewshow show];
}
else
{
viewcontroller1 *management =[[viewcontroller1 alloc] initWithNibName:@"viewcontroller1" bundle:nil];
[self.navigationController pushViewController:management animated:YES];
}
}
But I am not getting success. Please tell me what I am doing wrong.
I want to do validation.
if I have not sign it shows the message.
Please give me suggestion.
Thanks in advance!
I save Image and used condition
UIGraphicsBeginImageContext(self.drawSignView.bounds.size);
[[self.drawSignView.layer presentationLayer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// NSData *postData = UIImageJPEGRepresentation(viewImage, 1.0);
// Store the data
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *imageData = UIImageJPEGRepresentation(viewImage, 100);
[defaults setObject:imageData forKey:@"image"];
[defaults synchronize];
if(viewImage==nil)
{
UIAlertView *alertviewshow =[[UIAlertView alloc] initWithTitle:@"Warning!" message:@"Pease Sign" delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK", nil];
[alertviewshow setTag:1];
[alertviewshow show];
}
But it not work because it contain blank image.
解决方案
Please check this answer
UIGraphicsBeginImageContext(self.drawSignView.bounds.size);
[[self.drawSignView.layer presentationLayer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// NSData *postData = UIImageJPEGRepresentation(viewImage, 1.0);
NSData *imgData = [[NSData alloc] initWithData:UIImageJPEGRepresentation((viewImage), 0.5)];
int imageSize = imgData.length;
NSLog(@"size of image in KB: %d ", imageSize/1024);
UIGraphicsBeginImageContext(self.drawSignViewClient.bounds.size);
[[self.drawSignViewClient.layer presentationLayer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImageClient = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// NSData *postData = UIImageJPEGRepresentation(viewImage, 1.0);
NSData *imgDataClient = [[NSData alloc] initWithData:UIImageJPEGRepresentation((viewImageClient), 0.5)];
int imageSizeClient = imgDataClient.length;
NSLog(@"size of image in KB: %d ", imageSizeClient/1024);
int OCS=imageSize/1024;
int Client=imageSizeClient/1024;
if(OCS<3)
{
alertviewshow=[[UIAlertView alloc] initWithTitle:@"Warning!" message:@"Please do Signature " delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK", nil];
[alertviewshow setTag:1];
[alertviewshow show];
}
else if (Client<3)
{
alertviewshow=[[UIAlertView alloc] initWithTitle:@"Warning!" message:@"Please do Signature " delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK", nil];
[alertviewshow setTag:1];
[alertviewshow show];
}
else
{
//Write Your Code....
}
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