objective-c

Placeholder in UITextView

by

I made a few minor modifications to bcd’s solution to allow for initialization from a Xib file, text wrapping, and to maintain background color. Hopefully it will save others the trouble. UIPlaceHolderTextView.h: #import <Foundation/Foundation.h> IB_DESIGNABLE @interface UIPlaceHolderTextView : UITextView @property (nonatomic, retain) IBInspectable NSString *placeholder; @property (nonatomic, retain) IBInspectable UIColor *placeholderColor; -(void)textChanged:(NSNotification*)notification; @end UIPlaceHolderTextView.m: #import … Read more

How to link to apps on the app store

by

Edited on 2016-02-02 Starting from iOS 6 SKStoreProductViewController class was introduced. You can link an app without leaving your app. Code snippet in Swift 3.x/2.x and Objective-C is here. A SKStoreProductViewController object presents a store that allows the user to purchase other media from the App Store. For example, your app might display the store … Read more

Generating random numbers in Objective-C

by

You should use the arc4random_uniform() function. It uses a superior algorithm to rand. You don’t even need to set a seed. #include <stdlib.h> // … // … int r = arc4random_uniform(74); The arc4random man page: NAME arc4random, arc4random_stir, arc4random_addrandom — arc4 random number generator LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <stdlib.h> u_int32_t arc4random(void); … Read more

How do I create delegates in Objective-C?

by

An Objective-C delegate is an object that has been assigned to the delegate property another object. To create one, you define a class that implements the delegate methods you’re interested in, and mark that class as implementing the delegate protocol. For example, suppose you have a UIWebView. If you’d like to implement its delegate’s webViewDidStartLoad: … Read more

How do you trigger a block after a delay, like -performSelector:withObject:afterDelay:?

by

I think you’re looking for dispatch_after(). It requires your block to accept no parameters, but you can just let the block capture those variables from your local scope instead. int parameter1 = 12; float parameter2 = 144.1; // Delay execution of my block for 10 seconds. dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{ NSLog(@”parameter1: %d parameter2: … Read more

How to check iOS version?

by

/* * System Versioning Preprocessor Macros */ #define SYSTEM_VERSION_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedSame) #define SYSTEM_VERSION_GREATER_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedDescending) #define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending) #define SYSTEM_VERSION_LESS_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending) #define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedDescending) /* * Usage … Read more

How do I animate constraint changes?

by

Two important notes: You need to call layoutIfNeeded within the animation block. Apple actually recommends you call it once before the animation block to ensure that all pending layout operations have been completed You need to call it specifically on the parent view (e.g. self.view), not the child view that has the constraints attached to … Read more

Constants in Objective-C

by

You should create a header file like: // Constants.h FOUNDATION_EXPORT NSString *const MyFirstConstant; FOUNDATION_EXPORT NSString *const MySecondConstant; //etc. (You can use extern instead of FOUNDATION_EXPORT if your code will not be used in mixed C/C++ environments or on other platforms.) You can include this file in each file that uses the constants or in the … Read more

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)