4-29 Learning Experience

Error type:

Error:linker command failed with exit code 1 (use-v to see invocation)

This problem usually occurs when you add a third-party library file or when you develop multiple people.

This problem is usually a link error that is caused by a file not being found.

1. If it is multi-person development, you have completed the synchronization and found the following error.

1. Undefined Symbols for Architecture armv7:
2. "_objc_class_$_mypagelogviewcontroller", referenced from:
3. Objc-class-ref in BAIDUMOBSTATAPPDELEGATE.O
4. Ld:symbol (s) not found for architecture armv7
5. Clang:error:linker command failed with exit code 1 (use-v to see invocation)
6. The "Mypagelogviewcontroller" class appears in the error, you can find the. m file for this class, view his target membeship, and if not checked, click Tick. Then compile to view

button buttons by default, when the button is highlighted, the color of the image is drawn darker, and if this property below is set to No,

Then you can remove this function

button1.adjustsimagewhenhighlighted = NO;

By default, when the button is disabled, the image is drawn deeper, setting No to cancel the setting

button1.adjustsimagewhendisabled = NO;

When set to Yes, the button will glow when pressed

button1.showstouchwhenhighlighted = YES;

Cancel all events that have been added to the button: (This is more important, if two events are added two events will be triggered)

[Btn Removetarget:nil Action:nil forcontrolevents:uicontroleventtouchupinside];

Sometimes we want UIButton's title to align to the left, we set

Btn.textLabel.textAlignment = Uitextalignmentleft

is not useful, we need to set

Btn.contenthorizontalalignment = Uicontrolcontenthorizonalignmentleft;

But the problem comes out again, when the text is pressed to the left border, we can set

Btn.contentedgeinsets = Uiedgeinsetsmake (0,10, 0, 0);

Keeps the text distance from the left border by 10 pixels.

When is release UIButton released?

Whether to release the UIButton object in Dealloc depends on how the UIButton is initialized.

If you use [Uibuttonbuttonwithtype:uibuttontyperoundedrect] this way, you do not need to do the release operation, because this method is automatically released. If you are using [[UIButton Alloc]init], you will need to take an active release release operation.

4-29 Learning Experience