cocoa-touch

问题 I am using [UIColor colorWithRed:136 green:155 blue:218 alpha:1.0]; to change the background color of my table view cells. But for some reason the background just stays white. If I try [UIColor colorWithRed:0 green:155 blue:218 alpha:1.0]; the color changes. This does not make sense to me. Any advice or tips? 回答1: The parameter aren't a values of 0 to 255 but a float between 0.0 and 1.0: [UIColor colorWithRed:0.0f/255.0f green:155.0f/255.0f blue:218.0f/255.0f alpha:1.0f]; 回答2: The values need

问题 I use bellow codes to show data on TableView but when scrolling, data repeat and other data lost. - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [FileCompletedArray count]; } cellForRowatindexpath (): - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"CellIdentifier";

问题 I am working on adding in a settings bundle for my application as a cheap way of getting a GUI on my preferences. Is it possible to launch this from a button in my application or will my users always have to access it manually via the built in settings application? 回答1: They may have to go to the settings application, depending on how you do it. See this document, the Applications Preferences section. Here's the relevant section from the introduction: Adding your application preferences to

问题 I've a c function in my viewController.m. int abc(int a, char* b) { //do something } I also have a function -(void) callIncomingClass { UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect]; //set the position of the button button.frame = CGRectMake(100, 170, 100, 30); //set the button's title [button setTitle:@"Click Me!" forState:UIControlStateNormal]; //add the button to the view [self.view addSubview:button]; } Now I want to call callIncomingClass from within the function

问题 I've a c function in my viewController.m. int abc(int a, char* b) { //do something } I also have a function -(void) callIncomingClass { UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect]; //set the position of the button button.frame = CGRectMake(100, 170, 100, 30); //set the button's title [button setTitle:@"Click Me!" forState:UIControlStateNormal]; //add the button to the view [self.view addSubview:button]; } Now I want to call callIncomingClass from within the function

问题 In this question I asked for a good way to truncate a string to fit a given UITextView. Since there was no way provided by the SDK directly, I've ended up writing the recursive method below (only called by the following public method). However, this doesn't work unless I subtract a fudge factor of 15 (kFudgeFactor) from the field width when calculating the string's height. If I don't do that, the string returned is actually too long for the field, and displays in an extra line below it.

问题 When over freeing a pointer you may see an error such as "pointer being freed was not allocated" When debugging with the simulator, I add a build argument MallocStackLogging = YES - this allows me to use malloc_history in the terminal to track down where I have over freed a pointer. If I debug on the device with this build argument I get all sorts of console errors "cannot create stack log files" etc. Oddly, I get some over freed pointer errors appearing on the device, but not on the

问题 How can I create my own methods which take a block as an argument and which I can call later? I have tried following things. #import <UIKit/UIKit.h> typedef void (^viewCreator)(void); @interface blocks2ViewController : UIViewController { } -(void)createButtonUsingBlocks:(viewCreator *)block; @end - (void)viewDidLoad { [super viewDidLoad]; [self createButtonUsingBlocks:^(NSString * name) { UIButton *dummyButton = [[UIButton alloc]initWithFrame:CGRectMake(50, 50, 200, 100)]; dummyButton

问题 How can I create my own methods which take a block as an argument and which I can call later? I have tried following things. #import <UIKit/UIKit.h> typedef void (^viewCreator)(void); @interface blocks2ViewController : UIViewController { } -(void)createButtonUsingBlocks:(viewCreator *)block; @end - (void)viewDidLoad { [super viewDidLoad]; [self createButtonUsingBlocks:^(NSString * name) { UIButton *dummyButton = [[UIButton alloc]initWithFrame:CGRectMake(50, 50, 200, 100)]; dummyButton

问题 I have a UITableView where in some instances, certain sections have zero rows. My goal is that when this is true, I don't want any wasted space in the table view, it should look like there's no data. The problem I'm having is with the header and footer for the sections, which are showing even if there's no row and despite me overriding the delegate method to return 0.0f. Here's what it looks like - you can see the ~20p of gray space at the top there, headers and footers of about 10p each for