Function for Password validation

int length=[passwordString length];        

 if( length<8 || length >10 || (![self isPasswordValid:passwordString])) {

            

    NSString *alertMsg=@"Password length should be between 8 to 10  
       characters.Password must have at least 1 alphabet and 1 numeral(0-9)";

     
   [AlertView showAlert:alertMsg WithDelegate:self andTag:555];

   textField.text=@"";

            

 }

-(BOOL) isPasswordValid:(NSString *)pwd {

    

    NSRange rang;

    isValid=YES;

    rang = [pwd rangeOfCharacterFromSet:[NSCharacterSet letterCharacterSet]];

    if ( !rang.length ){

        isValid=NO;// no letter        

    }    

    rang = [pwd rangeOfCharacterFromSet:[NSCharacterSet decimalDigitCharacterSet]];

    if ( !rang.length ) {

     isValid=NO;  // no numb

    }

    return isValid;

}

Function to validate TextField and String

+ (BOOL) validateTextField: (UITextField*)textField

{

    if(!textField){

        return NO;

    }

    

    textField.text = [textField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

    if ([textField.text isEqualToString:@""]) {

        return NO;

    }

    return YES;

}

+ (BOOL) validateString: (NSString*)string

{

    if(!string)

    {

        return NO;

    }

    string = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

    if([string  isEqualToString:@""] || [string isEqual:[NSNull null]] || string == nil || [string  length]==0)

    {

        return NO;

    }

    return YES;

}

Better way to check empty string

//Check if we have any search terms in the search dictionary.

    if( (searchBar.text==(id) [NSNull null] || [searchBar.text length]==0 || searchBar.text isEqual:@""))

    {

         [AlertView showAlert:@"Please enter a search string"];

    }

Check device for iPhone 5

#define IS_IPHONE_5 ( fabs( ( double )[ [ UIScreen mainScreen ] bounds ].size.height - ( double )568 ) < DBL_EPSILON )

if(IS_IPHONE_5) {

   // It's iPhone 5

}

Calculate Height of Text from Width of an UILabel

UILabel *type;

type.frame=[self calculateHeightOfTextFromWidth:type withText:type.text];

-(CGRect) calculateHeightOfTextFromWidth:(UILabel*)detailLabel withText:(NSString*)text

{

    

    CGRect currentFrame = detailLabel.frame;

    CGSize max = CGSizeMake(detailLabel.frame.size.width, 500);

    CGSize expected = [text sizeWithFont:detailLabel.font constrainedToSize:max lineBreakMode:detailLabel.lineBreakMode]; 

    currentFrame.size.height = expected.height;

    return currentFrame;

}

Load an Image from existing location and from URL

AsynchImage.h

#import <UIKit/UIKit.h>

#import <QuartzCore/QuartzCore.h>

@interface AsynchImage : UIView{

    

    NSURLConnection* connection;

    NSMutableData* data;

    UIImageView* imageView;

}

-(void)loadImageFromURL:(NSURL*)url;

-(void)loadExistingImage:(UIImage *)image;

@end

AsynchImage.m

#import "AsynchImage.h"

#define ACTIVITY_FRAME CGRectMake(30, 35, 10, 10)

#define ACTIVITYINDICATOR_TAG 999

#define BORDER_COLOR [[UIColor colorWithRed:FLOAT_COLOR_VALUE(200) green:FLOAT_COLOR_VALUE(210) blue:FLOAT_COLOR_VALUE(232) alpha:1.0] CGColor];

@implementation AsynchImage

- (id)initWithFrame:(CGRect)frame {

    self = [super initWithFrame:frame];

    if (self) {

        // Initialization code

    }

    return self;

}

-(void)loadExistingImage:(UIImage *)image {

    

    if ([[self subviews] count]>0) {

        [[[self subviews] objectAtIndex:0] removeFromSuperview];

    }

    

    UIImageView* _imageView = [[UIImageView alloc] init];

    _imageView.frame = CGRectMake(2, 2, self.frame.size.width-4, self.frame.size.height-4); 

    _imageView.image = image; 

    _imageView.layer.borderWidth= 2.5f;

    _imageView.layer.borderColor=BORDER_COLOR

    _imageView.contentMode = UIViewContentModeScaleToFill;

    _imageView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);

    [self addSubview:_imageView];

    _imageView =nil;

    [_imageView setNeedsLayout];

    [self setNeedsLayout];

}

- (void)loadImageFromURL:(NSURL *)url{

    

    self.layer.borderColor = BORDER_COLOR

    self.layer.borderWidth = 2.5f;

    UIActivityIndicatorView *activityIndicator = [[UIActivityIndicatorView alloc] 

                                                  initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

    activityIndicator.frame=ACTIVITY_FRAME;

    activityIndicator.center=CGPointMake(self.frame.size.width/2, self.frame.size.height/2);

    activityIndicator.tag = ACTIVITYINDICATOR_TAG;

    [self addSubview:activityIndicator];

    [activityIndicator startAnimating];

      

    if (data!=nil) { data = nil; }

    NSURLRequest* request = [NSURLRequest requestWithURL:url                                       

cachePolicy:NSURLRequestUseProtocolCachePolicy

                                          timeoutInterval:30.0];

    connection = [[NSURLConnection alloc]

                  initWithRequest:request delegate:self];

}

#pragma mark - delegates

- (void)connection:(NSURLConnection *)theConnection

    didReceiveData:(NSData *)incrementalData {

    if (data == nil) {

        data = [[NSMutableData alloc] initWithCapacity:2048];

    }

    [data appendData:incrementalData];

}

- (void)connectionDidFinishLoading:(NSURLConnection *)theConnection {

      

    connection=nil;

    

    if ([[self subviews] count]>0) {

        [[[self subviews] objectAtIndex:0] removeFromSuperview];

    }

   

        imageView = [[UIImageView alloc] init];

        imageView.frame = CGRectMake(0, 0, self.frame.size.width-1, self.frame.size.height-1); 

        imageView.image = [UIImage imageWithData:data];

        //To crop Image

        imageView.image=[self imageByScalingAndCroppingForSize:CGSizeMake(100, 100)];      

  

        int resolution=data.length;

        if(resolution>800) {

            

        }

        imageView.contentMode=UIViewContentModeScaleToFill;

        imageView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | 

                                      UIViewAutoresizingFlexibleHeight);

        [self addSubview:imageView];

        [imageView setNeedsLayout];

        [self setNeedsLayout];   

        imageView = nil;

        // save the image to avoid multiple downloads

       data=nil;

    

       UIActivityIndicatorView *activity = (UIActivityIndicatorView *)[self 

                          viewWithTag:ACTIVITYINDICATOR_TAG];

       [activity removeFromSuperview];

}

- (void)connection:(NSURLConnection *)theConnection didFailWithError:(NSError *)error {

    connection=nil;

   

    UIImage *image = [UIImage imageNamed:@"userImage"];

    [self loadExistingImage:image];

    

    UIActivityIndicatorView *activity = (UIActivityIndicatorView *)[self viewWithTag:ACTIVITYINDICATOR_TAG];

    [activity removeFromSuperview];

}

//crop Image

- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize

{

    UIImage *sourceImage = imageView.image;

    UIImage *newImage = nil;

    CGSize imageSize = sourceImage.size;

    CGFloat width = imageSize.width;

    CGFloat height = imageSize.height;

    CGFloat targetWidth = targetSize.width;

    CGFloat targetHeight = targetSize.height;

    CGFloat scaleFactor = 0.0;

    CGFloat scaledWidth = targetWidth;

    CGFloat scaledHeight = targetHeight;

    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    

    if (CGSizeEqualToSize(imageSize, targetSize) == NO)

    {

        CGFloat widthFactor = targetWidth / width;

        CGFloat heightFactor = targetHeight / height;

        

        if (widthFactor > heightFactor)

            scaleFactor = widthFactor; // scale to fit height

        else

            scaleFactor = heightFactor; // scale to fit width

        scaledWidth  = width * scaleFactor;

        scaledHeight = height * scaleFactor;

        

        // center the image

        if (widthFactor > heightFactor)

        {

            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.1;

        }

        else

            if (widthFactor < heightFactor)

            {

                thumbnailPoint.x = (targetWidth - scaledWidth) * 0.1;

            }

    }

    

    UIGraphicsBeginImageContext(targetSize); // this will crop

    

    CGRect thumbnailRect = CGRectZero;

    thumbnailRect.origin = thumbnailPoint;

    thumbnailRect.size.width  = scaledWidth;

    thumbnailRect.size.height = scaledHeight;

    

    [sourceImage drawInRect:thumbnailRect];

    

    newImage = UIGraphicsGetImageFromCurrentImageContext();

    if(newImage == nil)

         

    //pop the context to get back to the default

    UIGraphicsEndImageContext();

    return newImage;

}

@end

Remove subviews (if already exists)

if ([[self subviews] count]>0) {

        [[[self subviews] objectAtIndex:0] removeFromSuperview];

}